Engine 89 5.0 5spd has a mind of its own, performance/idling issues

[Muttstang89]

Hello Stangers, this is my first real post here so please bear with me.

Well, to start out this little Snoozefest, Ill give you a little back story. The stang was orignially an AOD car. The orignal motor went south on me so we were able to find a low mileage replacement that included everything for a T-5 swap. We performed the conversion with relatively little issues a couple years ago and the swap really woke this car up...for a little while. As usual the T-5 syncros went bad after a good bit of abuse but there is no suprise there.

After the engine and tranny swap, I started adding some bolt on parts, exhaust, gears, and such. I do not run any type of power adders yet. The reoccuring issue here has been that the car seems to only want to run right when it feels like it. Most days it runs like ass , it doesnt really seem like time of day or temp matters unless its extremely hot out. Some times I will go out, hop in the car and tear ass down the road like theres not tomorrow and the majority of the days it will barely get out of its own way. To trouble shoot the car I have been through base idle resets, sensor diagnostics ( measuring ouput votage from various sensors), replaced bad sensors, pulled codes, compression test, etc, and nothing seems to make any kind of lasting improvement on this thing. But on a side not will running in this condition and driving it like a grandma, it bested a consitant 14.23 down the 1320 with 373 gears and launching at idle and granny shifting, not to bad for a fat guys car.

So after christmas of this past year, I have added (Dont shoot me just yet, I know all about the barage of comments about to come) GT40 exploder intake, and a trickflow stage 1 cam. Impatience got the best of me. Now before anyone gets all bent out of shape about "why did you do that and not heads blah blah blah", I have aquired a set of GT40P's that need to be put on, just havent made it that far. Now after doing the cam and intake swap, I was extremely impressed at how much that made a difference over the stock stuff, the car ran like a bat out of hell for a few days, then it went back to the same ole shenanigans. I found two vacuum leaks and fixed those and it didnt make a big difference in the symptoms/problems that I am having. And since the issue was happening before, I dont think that the issue is with the swap, but I understand that it can compound the issue.

Recently the stock 75 amp alternator took a dump. Here is what is crazy, and I have a feeling I know why this happened but ill wait for some responses, When the alternator died, we had jumped the car a few times to get it back home. At this point, the car was only running on whatever charge the battery had, I would say at most 11v at max, and it ran like a scalded dog. I grabbed second and it was all over the place just roasting the tires, I was pretty freaking stoked about it especially since it was doing this on already warm tires from highway travel. Sadly this was short lived. So that leads me to here, Upgraded to a 3g alternator that I had on sitting on the shelf, which was much easier than the write ups make it seem, and the first time we fired the car up and took down the street to make sure everything was good, it ran like a beast again, pulling my face off. We stopped at the local convience store and shut the car off for a bit, cranked her back up to go home and it was back to just bumming around and didnt have any ass behind it. I just dont get it.

Sorry for the book here, so now for the setup and mods:

5.0 stock block and heads
Busted T-5 Tranny #2
GT40 explorer intake/ with stock TB and relocated air charge sensor
Trickflow stage 1 cam
Full exhaust, shorty heads, offroad x-pipe into 40 series and tail pipes
70 mm mass air meter - factory Cobra style housing
New MSD Streetfire Coil (wich helped any higher rpm breakup that was ocurring)
3G alternator upgrade with appropriate wiring
Aluminum drive shaft
373 gears

Again sorry for the book but its at least a good amount of info to go off of from the start.
Thanks for your time and any help is appreciated.

 

[Noobz347]

I see no mention of codes ever being pulled. The description of symptoms sounds a lot like either a poor/intermittent connection between the EEC and the harness or a poor/intermittent connection between the harness and one or more sensors. It can also be a failing sensor but it would be one that would cause the EEC to go into limp mode (mass air sensor for instance).

The moral of this post so far is: Pull codes and post what you get.

 

[Muttstang89]

"To trouble shoot the car I have been through base idle resets, sensor diagnostics ( measuring ouput votage from various sensors), replaced bad sensors, pulled codes, compression test, etc, and nothing seems to make any kind of lasting improvement on this thing."

Noobz, I appreciate the feedback, I have pulled codes countless times and have repaired the issues that have been pointed out by them. Most of the common codes that I encounter are from the smog stuff, I forgot to mention that I had deleted all the smog equipment, pump, lines etc, and they are usually always present, the most recent codes have been and Lean O2 sensor reading issue which was corrected and other than that I get nothing.

 

[Muttstang89]

Idle Video Link

 

[Jace78]

Some stupid questions... IAC clean? MAF clean? My 90 was acting weird and I ran some Lucas fuel system cleaner thru it and changed the fuel filter/cap/rotor/plugs/wires and the difference was night and day...

 

[Muttstang89]

Jace, I have checked the IAC a few times, MAF is spotless, wires and plugs are just a couple months old, it has a msd cap and rotor button on it currently that is in decent shape (visually). My suspicions are leaning towards maybe a failing Fuel pump or Pump not getting the voltage it needs. Also, maybe the PIP in the Dizzy is going south too? These parts are really only the last few original parts to the car that have not been upgraded or replaced to my knowledge, my plan has been to upgrade the pump and sending unit soon anyways because of this reason. Ive checked for vac leaks a million times because it kinda acts like maybe it has one, but I havent found anymore of those either, unless the lower intake is pulling vacuum from the lifter valley or something. I did a vacuum test from the service port on the vac tree and the needle wasnt really steady but I have kinda attributed this to the cam, if i remember correctly the reading was in the 12 -14 range on the vac gauge. But theres always starting at square one i guess?

 

[madspeed]

have you cleaned the ten pins?

 

[Muttstang89]

yea Madspeed, I cleaned them a good while ago and checked them again after the intake swap and the ACT relocation since I had to dig into the harness anyway, I havent performed the mod to it that everyone suggest, as far as widening the pins so they get a better contact within the connector. But this may very well be worth revisiting though. There's a couple things I'm going to go over, in the coming days and check out.

Is there an actual "Limp Mode" that can be triggered, within these computers? I'm just curious as to maybe this is what is going on, something is triggering it to go into Limp Mode or something ?

Thank you for everyone's input so far, it is greatly appreciated!

 

[madspeed]

ect sensor? maf sensor? have you tried running it with the maf unplugged? Tried swapping distributor to a known good working unit? Take it to a good Ford mechanic?

 

[Noobz347]

What are the results of your KOER?

 

[Muttstang89]

Alright Gentlemen, did some trouble shooting today, KOEO test initially produced no codes, at some point after testing things it threw a code 96, I verified this by running the test 3 imes and produced the same results. I checked the power to the fuel pump at the pink and black wire and while the car was running it held a steady 13.60 volts so the pump is getting the power it needs through that connector at least but I dont know if maybe the relay is starting to go.

KOER I got the usual codes for the smog 44 and 94 (thermactor R and L) and a 33 which I have the vacuum line to EGR unhooked but that was to see if the EGR was the issue, just havent hooked it back up yet.

I put a vacuum gauge on the car again while I was doing some test while the thing was running, and it started out pretty low around 10hg, as I was setting the timing back down from 14 to 10 degrees base timing I decided to see what the vacuum gauge read when Increased the timing at idle. I took it up to about 20 degrees base at idle listening for any abnormalities, and the idle sped up and evened out of course and the vacuum gauge read close to 18 hg.

I set the timing back to around 11 degrees and she ran a little smoother through the gears than it did at the start of the day but still doesnt have the ass it has when it wants to act right.

Back to another question, could the computer be in limp mode of some sort?

Madspeed, the car will not even run if I unplug the MAF, unless I keep on the throttle but even then its spitting and sputtering, and I replaced the ECT sensor less than a 1000 miles ago, not that that means much but its "new"-er, and I haven't taken it to a local Ford Mechanic, mainly because I hate paying other people to work on my stuff when I am capable of doing unless it needs some specialty tools. I suppose I could give it a shot.

I Seriously appreciate you all helping me with all of this, I know these things can be a PIA to diagnose not seeing the vehicle.

 

[madspeed]

what injectors?

 

[Muttstang89]

19lb with the three hole pintle instead of the single point pintle. I have recently ran cleaner through them from a test rig and a switch that i rigged up, they all seemed to spray pretty evenly, because i thought that one of them might have been clogged. I caught what came out of them in a cannister and it cleaned a good bit of junk out of them.

 

[pearlnotchback]

19lb with the three hole pintle instead of the single point pintle. I have recently ran cleaner through them from a test rig and a switch that i rigged up, they all seemed to spray pretty evenly, because i thought that one of them might have been clogged. I caught what came out of them in a cannister and it cleaned a good bit of junk out of them.

Check the 10 pin connectors real good and not just for cleanliness. I had a problem similar to this and I came to find several broke wires where they go into the connectors. The insulation wasnt broke but the wires on the inside were. I fixed them and havent had a problem since.

 

[Muttstang89]

hey another symptom of this whole thing thats been happening since ive owned the car that comes and goes but here lately it has been every time i start the car, First start on a cold start (whether its cold, warm, or hot out) it starts then stumbles and then dies. Start it back up and it does the normal idle. Ive traded out the IAC a number of times between a few that i have and it pretty much stays the same, ive cleaned the plunger in them and such, But have yet to drop the coin on a brand new one. Anything else that would cause this issue you think?

 

[Muttstang89]

Pearlnothch, ill probably tear apart the 10 pins over the next week since i will have some time off for the holiday and the weather wont be too bad. I have two other Injector harnesses so if need be ill just swap them out, something like that would make sense, seeing as how brittle these wires can get over time, thanks for the tip man!

p.s. Did you just probe the wires and check for continuity or resistance?

 

[pearlnotchback]

Pearlnothch, ill probably tear apart the 10 pins over the next week since i will have some time off for the holiday and the weather wont be too bad. I have two other Injector harnesses so if need be ill just swap them out, something like that would make sense, seeing as how brittle these wires can get over time, thanks for the tip man!

p.s. Did you just probe the wires and check for continuity or resistance?

Actually lol I found this by mistake. I had been chasing this problem for about a month and I had the car running one night and reached back behind the intake to make sure the pcv was pushed in and the car died. So i cranked it back up and shook the piss out of the wiring harness and it started revving up and down and doing all kinds of crazy stuff and thats what led me to the connectors.

 

[Muttstang89]

Alrighty, shake the ever living piss out of harness and hope for the best, check! lol sounds good to me though. I will give it a look see. Thanks for your help man.

 

[Muttstang89]

Sorry it took so long to respond, been working and taking some time to test some things on this piece.

I do have the A9P computer as well.

1 - Yesterday, the first test of the last couple days was the Leak down - Checked my gauge on my fuel rail before starting and it read zero. I did 5 cycles before I tried to start it. Started it and it sputtered and died( like a bad IAC), I restarted it and it kinda sputtered a bit the idle went lower and surged up and down a bit then steady out to the usual junk. I let it run for a couple min and check the fuel pressure and it was reading a normal steady 35-38psi, with a quick WOT rev, the fuel pressure dips down into the 20's but rebounds back into the 30's as the vacuum comes back. I shut the car off and watched the gauge to see what happened, the pressure actually climbed to about 42psi with the car off, I let is sit for about 6 hours and rechecked, it was back to zero again.

2 - Today I went a little out of my mind, but I figured The only way to really know whats going on is to take stuff apart and see whats happening.
My cousin and I decided to drop the tank and check out the fuel pump to see if maybe there was some junk stuck in the sock filter or if maybe the sock filter itself was messed up. We pulled it all apart and everything looked like it should, It still has the factory Ford fuel pump, the hose had some surface cracks but nothing that looked to deep as to cause and issue, the sock filter was pretty clean, it had a little bit of junk on it but nothing major, but if it has been in the tank since 89 it was in pretty good shape. I cleaned it the best i could with some brake cleaner, for shigs i through the DMM on it to check the Ohms and it was a nice solid zero. I removed the fuel level sending unit to check and see if there was something obviously wrong with it, and it was clean and in tact. It has the case of only wanting to work when the tank is almost empty, most other times its all the way to the F. I sprayed it don with some brake clean and made sure to move it around while doing it to try and remove any grit that was in between the contacts on the arm. Conveniently enough it started working again, who would have thunk.

3. Here is the crappy part about this experience, when i was pulling the pump out of the tank I heard something moving around in the tank. After testing and cleaning the pump and such, I decided to probe around with my trusty magnet (in hindsight probably not the best idea). Originally I did this to make sure there wasn't any metal pieces in the bottom of the tank. I didnt find any small metal parts, the only thing I came up with was the gigantic baffle that use to be fastened to the tank. So at this point not only am I looking at upgrading the pump, I will now be looking at a new tank. Surprisingly enough the tank was clean and there wasnt any rust in it. By the way I had changed the fuel filter a couple weeks ago.

I reassembled everything and stuffed the pump into the middle of the baffle to hopefully keep it somewhat stationary or at least not floating all over the place in the tank until I can get the replacement.

4. Next we started it up, I had the neutral position switch unplugged for some reason under the car, so we plugged that back in. While it was running and up on jack stands, I started trouble shooting some other stuff. Shook and wiggled the crap out of the Ten Pins and twisted and messed with the wiring of any of the injectors that i could get to and there were no changes.

Unplugged the MAF while it was running and it died like always. Started it back up with it unhooked and it barely ran, had to give it some throttle to get some sort of steadiness to it. Plugged it back in and no change.

Next I was on to the O2 sensors, while it was running I unplugged them and the only change that I noticed was that the idle didnt surge as much as it had been but the car still sounded like it was misfiring or something like it has been. I let the car run for a little bit until finally it tripped the check engine light. We restarted the car with them unplugged and there was no change in anything. I plugged them back in while running and moved on.

I checked around all the vacuum lines and such moving them unplugging and capping them as I went and nothing changed. I took off the vac line from the FPR and capped it with my finger.The idle sped up a few hundred rpms and held steady but still had what sounded like cross or misfiring, im pretty sure on that note that i have the appropriate plug wires routed to avoid that.

So now it was time for the road test, and to my suprise it ran pretty damn good but it was still lacking what it could be.


The vid above is a mild 1st to second pull and had to let out of it because the road turns hard right. But as you can tell its roasting the tires down the street. When it runs at its worst it wont do this at all, sometimes wont even so much as bark the tires going to second.

I dont know what we did today but something worked, and we never took off the cable to the battery so the computer had not been reset.

What do you think.

Matt

 

[jrichker]

Cylinder balance test: use this to find dead or weak cylinders:

Revised 25 March 2012 to add necessity allowing the KOEO tests to finish before starting the engine and the need for a properly functioning IAB/IAC to run the cylinder balance test.

The computer has a cylinder balance test that helps locate cylinders with low power output. You’ll need to dump the codes out of the computer and make sure that you have the A/C off, clutch depressed to the floor and the transmission in neutral. Fail to do this and you can’t do the engine running dump codes test that allows you to do the cylinder balance test.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Be sure to turn off the A/C clutch depressed to the floor, and put the transmission in neutral when dumping the codes. Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.


Here's how to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and drivability problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, clutch depressed to the floor and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Cylinder balance test

If you have idle or IAC/IAB problems and the engine will not idle on its own without mechanically adjusting the base idle speed above 625-750 RPM, this test will fail with random cylinders pointed out every time it runs. The IAC/IAB must be capable of controlling the engine speed to run in the 1400-1600 RPM range. Playing with the base idle speed by adjusting it upwards will not work, the computer has to be able to control the engine speed using the IAC/IAB.

Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Let it finish the Key On Engine Off (KOEO) code dump. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. Remember to keep the clutch pedal (5 speed) depressed to the floor during the test. The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure


Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder balance test. Low compression on one of these cylinders rules out the injectors as being the most likely cause of the problem. Look at cylinders that fail the cylinder balance test but have good compression. These cylinders either have a bad injector, bad spark plug or spark plug wire. Move the wire and then the spark plug to another cylinder and run the cylinder balance test again. If it follows the moved wire or spark plug, you have found the problem. If the same cylinder fails the test again, the injector is bad. If different cylinders fail the cylinder balance test, you have ignition problems or wiring problems in the 10 pin black & white electrical connectors located by the EGR.

How to do a compression test:
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Your local auto parts store may have a compression tester to rent. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the throttle wide open, crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 psi. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.

See the link to my site for details on how to build your own blow down type compression tester.


Post any codes you get and I will try to help you fix them.