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| 88 Formula stuttering/misfire in drive (Page 1/1) |
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fierokid88
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NOV 12, 08:50 AM
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Back in August, i found an 88 fiero formula with a GT clip. Paid $1000 cash for it and was told it would run. Long story short, i got it running and running really good. I let the car sit over about a week and go to drive it to storage, 800ft down the road it will bog and surge. The RPMs will drop down to 500, shoot back up to 1500, and id have to idle it back home in which it would continue to do it in park. I have replaced the IAC, eliminated all vacuum leaks, Deleted the EGR, set ignition timing, replaced TPS with a known good one, cleaned the throttle body, cleaned all grounds, new plugs, plug wires, ICM, Distributor cap and rotor, tested pickup coil, Also has new injectors.
Yes the tank is full.
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Vintage-Nut
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NOV 12, 09:14 AM
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To ME, it is better to have an operating EGR system, than 'tricking' the ECM into thinking that the valve is really not here.
A working EGR system creates no performance loss & reduces fuel consumption.
"Fooling" the ECM when the EGR isn't here, it can cause the engine to run 'rich' at times.
Did you get the chip re-programmed to delete the EGR function?
Perhaps, this may be the problem....
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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles[This message has been edited by Vintage-Nut (edited 11-12-2025).]
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fierokid88
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NOV 12, 09:53 AM
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| quote | Originally posted by Vintage-Nut:
To ME, it is better to have an operating EGR system, than 'tricking' the ECM into thinking that the valve is really not here.
A working EGR system creates no performance loss & reduces fuel consumption.
"Fooling" the ECM when the EGR isn't here, it can cause the engine to run 'rich' at times.
Did you get the chip re-programmed to delete the EGR function?
Perhaps, this may be the problem....
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I was told on facebook that i can jumper out 2 wires on the EGR solenoid plug to trick the ECM. I only deleted the EGR because the solenoid was bad and it seems hell to find another one. Otherwise i wouldn’t mind running it. I did not reprogram it.
If you or someone you know has the solenoid, i’d be willing to buy it.
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Vintage-Nut
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NOV 12, 10:27 AM
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Patrick
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NOV 12, 04:27 PM
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| quote | Originally posted by fierokid88:
I was told on facebook that i can jumper out 2 wires on the EGR solenoid plug to trick the ECM.
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You were misinformed.
What is your fuel pressure when the engine is running? And how quickly does the fuel pressure drop when the engine is turned off?
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fierokid88
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NOV 12, 04:59 PM
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| quote | Originally posted by Patrick:
You were misinformed.
What is your fuel pressure when the engine is running? And how quickly does the fuel pressure drop when the engine is turned off?
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I figured as such. So i was able to get my hands on a wireless pressure gauge for the night. I have 45.x on prime, it quickly drops down to 35 and drops lower pretty fast aswell. The pump is new as when i bought the car there was no fuel pump prime. The original pump still works, it was the connections that were dirty. I replaced the fuel pump with the one i got off of TFS anyway since i had already spent the money on it.
I drove the car (tried to back out of the driveway) and the fuel pressure was pretty consistent around 35-37 PSI. Maybe one of the lines is cracked? I had it up on the lift and did smell gas a while under it but didnt think much of it. After I put the new fuel pump in and rid of most of the vacuum leaks, thing ran really damn good. Had a few hiccups here and there due to cracking in the EGR tube which has been fixed. Solved all vacuum leaks since then.
Soooo i guess im going to drop the tank tonight!
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Patrick
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NOV 12, 05:24 PM
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| quote | Originally posted by fierokid88:
I drove the car (tried to back out of the driveway) and the fuel pressure was pretty consistent around 35-37 PSI. Maybe one of the lines is cracked?
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That fuel pressure is definitely too low. Before you drop the tank, maybe have a look at some of the suggestions made in this thread. It could possibly be a leaking fuel pressure regulator and/or injector(s).
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