hit a bump, sho goes shlump....

[wampaku]

strangest thing that keeps getting worse... it started out like this: as i was eating a mustang (et al) for breakfast and would hit a bump down the road my sho would hesitate; almost like i released the gas pedal for a second and then went wot again. strange but tolerable. it has progressed to the point where if you hit a bump the car will do one of two things: die completely and require you to pull over and restart (this sometimes takes several minutes), or a transient stall that will self-restart. cant say for sure but it seems to be the most affected when the right front tire hits a bump. another way to duplicate the symptoms is to raise the hood and let it fall closed. this results about 90% of the time in the transient stall. you can hear the engine quit and then restart before it stops turning over. what could it be or how would i self diagnose the problem. hate to take it to a mechanic and pay $70+ just for a diagnostic. i realize a scanner type of device that would allow monitoring of different parameters and/or sensors while my wife slams the hood repeatedly would be most likely be the best way, but what scanner would do that with OBD 1? Autozone sells code readers only, and it is my understanding that those only read existing codes. the check engine light isn't on. and i am not willing to drop the money on the off chance that it throws out a useful code when the hood is shut.
I have been under the hood wiggling, banging with a rubber mallet, poking, prying etc at about all i can see trying to duplicate the problem but the only two ways to do it are either hit a bump, or slam the hood.
Any ideas on what it could be, or how to figure it out?

 

[wampaku]

p.s. its a 92 MTX

 

[93rev2sev]

I would say that since a lot of inertia is needed (bump or slammed hood), that it must be a heavy wire.

I would check the battery connection at the starter.
Then I would check the battery connection to the power distribution box.
Then I would open the power distribution box and start wiggling fuses.
Then I would goto the trunk and wiggle the fuel cut off switch around.
Then I would saunter(yeah, saunter) to the passenger firewall and start playing with the grounding strap, DIS module, CPS connector, Cam sensor connector(don't think this one matters once the car is running), etc

Does the car have an alarm? If so, the dang thing might be thinking you are being broken into and cutting off the ignition (doubt it though if the symptoms got worse over time).

Try jacking it up and letting the jack down quickly to see if it happens with the hood up...just dont hold onto the radiator support when you let the jack go...hoods slammed on fingers hurts for weeks.

 

[wampaku]

what is a DIS module? sorry, i just don't know....

 

[93rev2sev]

Distributorless Ignition Module. Its the module that is on the passenger side of the intake manifold. It's a grey(usually) rectangular box with connectors fore and aft.

That module MUST be grounded well. It's grounded to the intake manifold by the metal plate that sits flush to the mounting boss.

The intake manifold is, in turn, grounded to the firewall with a braided metal strap bolted to the intake manifold. I think it's a flat, braided wire with a black plastic sheath.

I had this problem when my subframe broke. It rusted through the bushing mount area. The whole engine cradle dropped a good inch in the back passenger corner. This caused the DIS module to be disconnected when I hit a bump or took a corner too fast(it snagged on the engine roll damper bracket). The car would stall but it always started back up so I thought I needed a Crank Sensor...until I let my Girlfriend borrow the car, It stalled for good and she had it towed. The mechanic was stumped. I showed up and looked around the compartment...saw the DIS connector was loose, secured it with a zip tie and drove it home...the next Saturday was subframe day.

 

[95azSHO]

Check the conection of the MAF sensor? on the drivers side is the air filter next to it is a plug conector with retaining clips I broke mine and made it loose try that. If it is it a hose clamp will take care of it.

 

[wampaku]

ok, checked all of the above and all seem ok. batt connection at the starter was about 1/4 turn loose, but i tightened it up. after i checked all of the above i checked the codes via http://www.shophoenixproject.com/eec/eec.htm and got the following: 511, 122, 157, 211, 215, 216, 219, 221??, 326, 327, 336, 337, 528, 542. every thing else is "good." just did the hood slam test and it did the intermittent stall again...

 

[wampaku]

ok, i realized last night that most of those codes were from me pulling wires n' such while the engine was running trying to figure out what the problem is. so this morning i cleared the computer memory and did the slam test. i got "pcm detected coil 2 primary circuit failure (code 216)", and codes 542 & 543. both are " fuel pump secondary circuit failure." now what?

 

[wampaku]

update... i figured it out. tapped the eec or pcm connector and viola... stall. pulled the computer and it was the superchip connected to the back of the computer. turns out it was loose and would jiggle when i hit a bump. so i unplugged the chip and the car wouldnt stall. i am securing the chip so it wont flop around anymore. i guess the coil and fuel pump codes were a result of the chip. it has an after market high flow fuel pump, and i guess the chip did something to the coil and fuel pump. Lose the signal from the chip, and the aforementioned symptoms go bang. thanks y'all.

 

[93rev2sev]

DOH!

I shoulda thought of this....nice find.

 

[Eric VerValin]

Thank you thank you thank you.... Tom remember when I was down the road in Detroit... this was my problem.. strangest thing, it happened again today. Same kinda codes, 219, 221. Funny how shit works out on here somedays.

I also have an oddball TP sensor I think has been going out, but yea, same thing alarm, chip, 92 mtx under the hood... lol weird...

 

[SHOCH]

ok, checked all of the above and all seem ok. batt connection at the starter was about 1/4 turn loose, but i tightened it up. after i checked all of the above i checked the codes via http://www.shophoenixproject.com/eec/eec.htm and got the following: 511, 122, 157, 211, 215, 216, 219, 221??, 326, 327, 336, 337, 528, 542. every thing else is "good." just did the hood slam test and it did the intermittent stall again...

Glad you found the problem but this is the funniest post ever.
14 codes followed by "everything else is "good"". SHO life lol.