need help. car was running good, all of the sudden it started missing.

axeman

axeman

Founding Member
Feb 9, 2001
1,348
0
36
Elizabethtown, PA
#1
just got done doing some suspension work and decided to take the car for a spin. it was running good, didn't get to operating temp yet and all of the sudden it starting missing. within a split second it just starting making a chugging noise and you could feel the car shake with it. plugs and wires are fairly new, timing and fuel pressure are good. got any ideas of what it could be? i guess i could check the codes, do you think something like this will show up?
 

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#2
well, i ran the codes and the system passed when the engine was off. while the engine was running the following showed up:

code 21-coolant temperature sensor out of range
code 33-canister or egr valve not operating properly

i don't think the coolant temp sensor is a problem but, i'm not sure about the egr or canister. i put a trickflow street heat intake and AFPR on last year, and i needed to dent the egr valve in order for it to fit but the car has been running great until today. maybe it's just dirty?
 
#3
did you run the balance test (for the injectors)? helps to rule stuff out. i dont know that what codes you got would lead to a miss.
you can stick an inductive timing light on the wires and pull the trigger to see if you have juice at all wires.
thats all i got.
good luck.
 
#6
in whatever test source you use (a manual, the book with code scanner, a site on the net, etc). its generally the third or fourth test (my scanner book has the KOEO, KOER, timin check, something else, then the balance test). i assume you have a book to reference. if not i will look for a source online (better than me trying the regurgitate the test). one of the three sites Jrichker always lists has the test, IIRC.

the idea with the timing light: if the light flashes the same rate for all plug wires, chances are, you are good to that point. a good quick check (same idea as grounding each wire, but much faster). if you have a dead wire, you will find it.

i got a miss awhile back. did the timin light test, then fuel pressure check at Schrader valve. then balance test. found cylinder two was a no go. the balance test is cool, cuz if it finds something amiss (pun intended) with an injector, it will retest it different ways to find what criteria the injector is not meeting.
good luck.
 
#8
thanks for the help. after work i will try the timing light trick and the injector test. i know my fuel pressure is fine because i have a mechanical gauge on my cowl hooked up from the schrader valve. hopefully it's just one of my wires because it sure feels like it's not running on all cylinders. do you think it could be my gas that's frozen or slushy?

i have both a chilton and a haynes repair manual. sometimes i just sit down and read them and i don't ever recall seeing the injector test in there.

so what was wrong with your number 2 cylinder?
 
#9
Why are you choosing to ignore the code 21? The computer won't just make up the codes - it picked up something funky with the temp sensor - it's worth pursuing. Check the voltages. At lower temperatures (approaching freezing) the output of the ect sensor should approach 4-5V. As the car warms up, the voltage decreases. At 100F it should be around 2.2V. At 150F it should be around 1.2V. At 192F (t'stat temp) it should around .61V. So, with a digital voltmeter, you should be able to get an idea of what the sensor is doing. Hook your meter to the wires coming out of it.
 
#13
Axeman said - "i didn't have the car warmed to operating temperature, so i'm pretty sure that code would come up. "

No - that wouldn't cause a code to come up in and of itself. As long as the computer is reading a signal from the sensor that's within the range of what it expects, it won't generate a code. And it expects a cold temp/high voltage at that sensor on a cold start. If what you suggest is true, the check engine light might come on or codes would be generated everytime the car's started cold. And that's simply not how it works.

If you want to trouble shoot problems with electronic fuel injection systems without just guessing at it, spend a few dollars on a book by Probst about the Ford EEC systems. Best money you'll spend diagnostically. They have tables of expected values for things like that - that's where I got the data. When I first built mine and was having idle troubles, I used the data in the book to test each of my sensors with a volt meter - very easy to do; it and the codes helped me verify what was working correctly and what wasn't. Get your car up to operating temp and check the voltage on the ECT - it's located in the metal tube running from the intake manifold back to the heater hose just to the left and behind the distributor. At operating temps, if that voltage isn't around 1.0V to .6V (depending on the temp t'stat you're running - 160 should be closer to 1V; 195F closer to .6V), then you've got a fritzed ect sensor. It's not magic - the data's out there, you just have to put your hands on it.
 
#14
well, i did the timing light trick and found that the number two plug wire was only firing intermitantly. went to get replacement wires from advanced since they are lifetime replacement(i get new ones every year or so free), forgot i bought them at autozone not advanced. so now i have to wait until tomarrow on my way home from work. think that would do it? i won't be checking the egr and ect until then because i don't feel like putting the wires back on just to take them back off. car ain't going anywhere in this freakin snow anyway!

guess i was wrong about the ect (code 21)? that's why i'm on here gaining some more knowledge. :p but my check engine light never came on at all through this ordeal. :shrug: thanks for the voltage numbers michael. hopefully the test numbers are ok.
 
#15
You could measure the resistance of the wire in question before you replaced - unless of course they're old anyway and likely in need of replacement. We're all on here to learn - for the most part; I can appreciate that. If you need more detailed data on the sensors, pm me and we'll figure out a way to get it to you. I've got more temp. points, and the book also has a graph of the voltage/temp. function so you can interpolate any temperature you wish. But knowing what it should be when it's cold outside, and what it should be at operating temp gives you a couple of points to work with - should be enough to do a brief check. By the way, not all error codes set off a check engine light - as if it weren't confusing enough.
 
#16
i'm just going to wait until tomarrow. wires will be free anyway. i might as well throw some new plugs in there a while too. i'll check the ect with the numbers listed above, that should be fine for now. if code 21 comes up it's probably time to replace the ect isn't it? i mean, how can you get the voltage readings back within specified range? i've never replaced the ect as long as i've owned the car, i just swapped it over when i put the new intake on last year, could be the origional. :shrug:
 
#17
outstanding advice from Michael, as we only expect. :nice:
as for the ECT, you asked,
"i mean, how can you get the voltage readings back within specified range?"
as i understand, its more a matter of how well the sensor is conducting at specified temps. they get old (i dont know on a degredation level why), and dont read correctly. i would say to get a new one at the parts store while you are there. should be under 10 bucks. while i agree with Michael on not blindly tossing money at sensors, im not sure he would disagree that since you are getting the code, and you admit the sensor is of an unknown age, to go ahead and stick a new one in. so cheap, why not (my thinking).

as for the plug wire thing...did you do an additional test? i use the test i gave when ruling things out. once a bad wire is found, further investigation is usually performed, as Michael mentioned (ohming it out, etc). you could swap two wires (swap on cap and plug), and see if the same wire is still intermittant. i know your wires are free, but doing further tests would confirm your culprit, so if that is not the problem, you havent wasted any time (i hate having sick cars). i would get some new wires regardless. just a good idea, and the price is right. :)
good luck
 
#18
Yeah - if it's not producing the correct voltages, replace it. $13 at AutoZone as I recall; more if you want to use the Ford part. If you're careful, and have everything ready to go, you can unscrew it, hold a rag over the opening so you don't lose much coolant, then quickly screw the new one in. Place a rag underneath the metal tube to absorb any coolant you do lose. That ought to be a fun piece of repair in this weather - hope the garage (if there is one) is heated!! Good luck.
 
#19
i'm sure michael is greatly appreciated around here. he's got my vote anyway. :nice: i may just go ahead and replace the ect. since i'm going to be at autozone i'm going to pick one up. after i put the new plugs and wires on i am going to check the old ect before putting the new one on.

garage is heated with a torpedo heater. sucker stinks though, makes all my clothes smell like kerosene. gotta wear gloves because all my tools are ice cold. gee, can't wait to install my new gears. they'll be ice cold too. i guess i could sit them in front of the heater for a little while huh.
 
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