95 Mustang GT RPM stumble, shut off, ping, PIP, EGR, Vacuum

soonerkid

New Member
Oct 23, 2005
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I have been battling a few things for the last few months. If anyone can relate, please share what you know.

History:

1995 Mustang GT Convertible Stick
100K+ miles
No mods
New Autolite Copper Plugs
4 year old MSD coil, wires, cap and rotor
2 year old K&N air filter

5 years ago when I got the car (family freebie) the car would occasionally die and restart automatically on the highway. Happened a few times usually when it was hot out. Changed out coil, wires, cap and rotor as mentioned above and was hoping to advance the timing a bit. Everything over 10 degrees was giving me a very light ping at full throttle. Since I never gun it anywhere, I set timing back to 10 and never had an issue. Car never shut down while driving again. Also, I ran 93 octane to mask the chance of pinging. Probably not the best thought but I didnt like the light ping. Higher octane kinda worked...

Car started running a little rough this summer especially when I was driving traffic (Houston). Noticed I was getting some pinging at high throttle, not WOT, just when passing people or goosing it to merge on the higway. I normally drive 30 milles a day with no traffic so the problem was not a daily issue. Moving on.

So, I have been nursing a leaking dying compressor for a year. Had to top off regularly during the summer. Compressor finally blew yaddy yadda. New A/C compressor and related parts installed 2 months ago. Wow, this is what A/C feels like??? When the compressor kicks in, its noticeable. Maybe not to my passenger but I can feel it. Problem? Not sure.

Car sat at airport for 5 days while I was on business. Driving home in and out of traffic on a really freakin hot September day, car dies on me on the highway just like 5 years ago. This time it doesnt start back up. As I pull over (not stopped yet) I get it started back up by cranking it. Get almost home and it dies again. Had to wait 5 minutes before it starts.

So then I get on StangNet and start searching. Best thing I found was distributor, in particular the PIP. So, I did this and made a little writeup:
http://www.stangnet.com/mustang-forums/823694-rebuild-install-pip-distributor-stator-pick-up-pickup.html

Went for a test drive and car ran great for a day. Im pretty sure the computer was recalibrating so my issues didnt come up till the next day.

So this happens:
YouTube - 1995 Mustang RPM issue
Watch at 15-18 second mark. RPMs flutter. You can really feel it jerk at 30mph and lower gears but all issues are at the 1800-2000 rpm mark.

Ran a can of seafoam through the intake vacuum line for fun and nothing changed. I even let the seafoam sit for 5 hours. I barely got any white smoke either.

Now im thinking, what did my mechanic do? Talked it over with him about electronics and what was touched and we found nothing damaged or much electrical near the A/C parts for that matter.

I started cleaning and swapping parts one at a time. Heres my list:
Checked air filter. Removed K&N and replaced with clean stock FRAM. No change.
MAF cleaned with q-tip. No dirt. No change.
IAT cleaned. No change.
IAC cleaned. No change.
Swapped IAC. No change. Old IAC back on.
Swapped TPS. No change. Old TPS back on.
Now Im clueless. Really thought this was throttle related because it only happend at constant 1800-2000 rpms in any gear.
Hmm. How bout the EGR? This caused some NOX issues on my old Bronco, lets take a look. Cleaned everything, not much carbon. No change.
Changed EGR sensor. No change. Old sensor back on.
Then I pulled off the vacuum leading to the sensor just for fun. The stumble from my video above is gone. Wierd.
Check vacuum lines and found that little solenoid under the passenger wheel well cover. This has to be my vacuum issue. Swapped it, reconnected EGR vacuum line and no luck. Put old solenoid back on.

Changed spark plugs. All were identical and had an enlarged gap (.060) with a grey white color. Something I read said it looked like plugs with timing issues.

So, thats the list. All the cheap parts I could think of and none worked. EGRs are not cheap so I havent changed it yet. I really didnt think disabling it would be an issue. The only way the car will run semi decent is with the EGR vac line removed and plugged. I get a CEL only with vac line plugged. No codes any other time during the entire process above.
Also, with EGR disabled, my gas mileage is down from 290 a tank to 170 (edit, more like 220) and the pinging is awful at partial throttle mainly in 2nd and 3rd gear. Something is WAY off here.

If you made it this far, thanks for reading. I am open to any ideas. Let me know...

Distributor maybe?
Computer problem sending wierd info to the EGR vac solenoid?
Fuel pump?
Fuel filter?
 
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sixt9coug

Member
Sep 30, 2009
222
3
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Norwalk SoCal
I had something similar that I had a hell of a time tracking down. Mine was cured with a new PIP and reluctor wheel. My timing was all over the place though and I had nasty pinging and almost a rev limiter effect at around 3K rpms.

Changed it with a good used OEM PIP and it has been fine ever since. If you can somehow get a known good distributor and module I would start there.
 

bayellowstang

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Apr 25, 2003
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Carlisle, PA
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Disconnecting the EGR will cause a lot of detonation at cruise/lite throttle. I just disconnected mine not long ago and had to take 3+ (still tweecing it) degrees of timing out of the cruise/light throttle tables. As for the rest of it good luck. Nothing worse then trying to diagnose a intermittent problem.
 

soonerkid

New Member
Oct 23, 2005
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Thanks guys. Im going to back off the timing tonight until I can find a known good distributor. I am hesitant to buy the cardone due to the fact that they dont always replace the PIP. But a new dizzy is $$$$$$.
 

toyman

SN Certified Technician
Jul 19, 2007
1,944
53
79
Vernon BC
Thanks guys. Im going to back off the timing tonight until I can find a known good distributor. I am hesitant to buy the cardone due to the fact that they dont always replace the PIP. But a new dizzy is $$$$$$.
I thought you said you replaced the PIP in your first post. Are you experiencing shaft wear issues with the existing dizzy? Just confused here. You make no reference to pulling codes other than getting a CEL with the vacuum removed. Have you actually pulled codes and what were the results? My first thought was that the MAF has died but that shouldn't cause the car to stall but will create driveability issues. The other item to check is the HB. If it has spun timing readings are useless. Check to see if there is any wobble or rubber protruding between the outer and inner rings on the engine side. As for fuel issues you will need a pressure gauge before any conclusions can be drawn.
 

soonerkid

New Member
Oct 23, 2005
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I thought you said you replaced the PIP in your first post. Are you experiencing shaft wear issues with the existing dizzy? Just confused here. You make no reference to pulling codes other than getting a CEL with the vacuum removed. Have you actually pulled codes and what were the results? My first thought was that the MAF has died but that shouldn't cause the car to stall but will create driveability issues. The other item to check is the HB. If it has spun timing readings are useless. Check to see if there is any wobble or rubber protruding between the outer and inner rings on the engine side. As for fuel issues you will need a pressure gauge before any conclusions can be drawn.
PIP was changed but all the latest problems came after the PIP swap. The dizz looked fine when I took it apart, very little play and the parts were all still press fit tight when I finished.
As for codes, I mentioned there have been no codes after any of the parts swaps. I gave it a day or more of driving after each part swap to let the computer catch up and throw any codes. The only code I ever got was when the CEL was on due to the EGR being unplugged.
I will check the balancer tomorrow. That is definately a possibility.

One more note, when I pull negative cable and reset the computer, the car runs really well for the first 5 minutes. Then something triggers the EGR solenoid to send a very strange vacuum pulse to the EGR at constant throttle. Thats when the stumbling kicks in. So unless the distributor/timing is connected to the EGR somehow, I have two unrelated problems.
 

soonerkid

New Member
Oct 23, 2005
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Timing issue fixed. I was reading my balancer marks wrong. I have been over timed by about 8 degrees. That fixed the rough idle and bad performance.

Still dont know the wierd 2000 rpm flutter related to the EGR. EGR holds vacuum just fine and the solenoid is sucking about 7 hg at 1800 RPMs.
 

95Vert383AOD

Active Member
Jun 10, 2008
1,132
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Providence, RI
Have you checked the TFI ignition module?.... its on the front of the passenger strut tower. BTW i've heard of pips being crap from the parts store. The pip you want is the cobra 5.0/truck 351 (same part number) Its supposedly better than the reg GT one.

Theres the dynamod module which is supposed to be better. for the price difference on a generic one its worth a try. i've ran it for the past 3 years.

1994-95 Mustang 5.0L & 5.8L Dyna Mod Tfi Ignition Module by Performance Distributors at LRS - Same Day Shipping!
 

soonerkid

New Member
Oct 23, 2005
10
0
1
I have isolated this to a vacuum line problem related to the EGR. I replaced the EGR tonight and once again, no change.

However, the other night, I put vacuum on all the lines under the right fender related to EGR. On my car, this is the red and green vacuum lines. When I put vacuum on the red line, I heard a crinkle sound. Something you would hear if you squeezed a very thin plastic bottle. I could not isolate the noise but I think it is the check valve (small blue connector) connected to the air injection lines. I guess the air injection shares the same red vacuum line from the intake manifold. After I sucked all the lines over and over, the car ran absolutely perfect for 10 minutes. Mind you, this was with the EGR connected and the car at full operating temperature. I felt more power, more punch and the the car had the best idle ever. This was short lived and the jerky pulsing rpm issue came back.

So, I have isolated it to the vacuum line and now have to find a check valve to try next. Till next time...
 

soonerkid

New Member
Oct 23, 2005
10
0
1
Problem found in one of the following:
Thermactor Air Bypass (TAB)
Thermactor Air Diverter (TAD

Anyone know what to look these up under at Autozone or Advanced? I cant find them.
 

alleymad95GT

Member
Jul 14, 2009
204
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16
Okemos, Michigan
Problem found in one of the following:
Thermactor Air Bypass (TAB)
Thermactor Air Diverter (TAD

Anyone know what to look these up under at Autozone or Advanced? I cant find them.
Like this?

Advance Auto Parts: Air Management (Diverter) Valve by BWD - Part EC1180

That's the only one I can find...

Have you thought about going this route?

http://compare.ebay.com/like/390252355754?ltyp=AllFixedPriceItemTypes&var=sbar&rvr_id=162794669111&crlp=1_263602_304662&UA=WVF?&GUID=eb5571ef12b0a0a9eef07170ffe30970&itemid=390252355754&ff4=263602_304662