Engine misfire and backfire, need help

scbird1

Registered User
Engine misfire and backfire, UPDATE on last page

Im working on a 89 here and have run into a wall and can use some imput.
It starts but chugs and will barely stay running if you give it half throttle.
Here is what has been done thus far> Every sensor has been changed with known working ones including the coil,dis,computer, ignition switch,fuel pump relay,FPR. The car had about a qt. and a half extra oil, found out it was gas in the oil. Drained it out and replaced oil. its got to be getting good fuel. It has good spark on all plugs. Replaced the balancer,crank sensor= no change. Had the top half of the motor off to make shure all vacume lines and intakes were sealed. Car had even compression when checked. Took off the oil cap to make shure rockers were rocken, they were. No codes from scanner, gives me a {11 11} every time on KOEO and no stored codes. I pulled the wires off the maf , cam sensor, octane plug, spout connector nothing make a diffence.
Im just out of ideas unless it jumped timming but how can you tell untill you have the chain cover off? anyone have any ideas?
 
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When a engine dose not burn the fuel it seeps past the rings and down into the pan. The injectors still work like the motors running even when cranking.
 
Dumb question, but did you change your plugs? I had some simmler problems turned out to be 2 filed plugs.
 
Wires and plugs have been changed. Nothing I have done changes the way it runs. Its as if its way out of time. I realy need some advice here. Im working on this for a fellow SCer who has yet to drive the legendary super coupe.
 
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When you replaced the computer was it with the right model year, or transmission? Could that be causing your problem? Maybe the car was destined to be a parts car!! Hopefully not,
Phil
 
Ok would anyone like to take a dumb guess? im just out of things to check for. Im down to 2 things here. ether its mechanical or possable wires grounding out. Hell im at a loss here
 
I swapped one in from a 92 5 speed and this is a 89 5 speed. It ran exactly the same but threw a bunch of codes. I put the right one back in. Just thought I would try anyway. I have herd that these engines will run without a cpu in limp mode but this one will still not run. It fires right up and dies ,backfireing and chugging.
 
scbird1 said:
Ok would anyone like to take a dumb guess? im just out of things to check for. Im down to 2 things here. ether its mechanical or possable wires grounding out. Hell im at a loss here

Okay here's my guess...your getting way to much fuel and the cylinder walls are probably washed down. Check the fuel pressure...if it's not holding about 38-40 psi for at least 10 minutes after turning the key off (after cranking for about 10 seconds), then the diaphram is probably ruptured and allowing fuel to leak into the intake manifold from the vacuum/boost refrence hose that attaches to the top of the regulator.

David
 
I have two ideas that i have had come up on SC.
timming off a little the other is the wires are not in the right order on the injectors.
 
Well the FPR has been replaced and it holds pressure for more then 10 min.
Wires on fuel injectors on 89`s are marked so you can`t get them wrong but I checked the colors anyway. Ignition timming is controlled by the computer. Valve timming is set by the timming chain. This car went south and then was sold. So the new owner was told that the blower was shot. He put on a used blower and the car ran the same way. What would happen if a rag was left in the intake? Ok im reaching but have no where left to go but inside the motor.
 
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Hey I know we were talking about a possible bad ground. Could that be a source of the problem here? Wouldn't that cause intermittent problems? Just throwing stuff out too.
Phil
 
You cannot.......

You cannot run a 92 PCM in a 89 car. It will cause all kinds of problems. The PCM pinouts are different and the car will not run correctly.

I agree with David, the fuel pressure regulator is probably shot. Since it's dumping fuel, the regulator is allowing fuel in in excess of needed. You can put a vacuum gauge on the FPR and see if it holds vacuum. That is the only real test for it.

Also, make sure the fuel lines are not pinched. A pinched return line will DUMP fuel!!!

Change the PCM to either a 89 auto or manual or a 90 5-speed. The 90 auto PCM had no EGR and will run "OK" just different.


Don
 
Thanks for the replies. The fuel pressure regulater was changed and the correct ECM is back in the car. No pinched lines. The fuel dump is from trying to start this thing with every change we make we try to start it. Will keep changing oil till its figured out. Next will be a partial tear down. :confused:
 
Double check the spark plug wires and make sure they are on the coil pak right.... if your using the Helmes manual (I think thats the manual) supposedly the illustration there has it wrong...........

Frit
 
fturner said:
Double check the spark plug wires and make sure they are on the coil pak right.... if your using the Helmes manual (I think thats the manual) supposedly the illustration there has it wrong...........

Frit
You right but the later issues have it right. I have a Ford service manual for a 89 tbirds. I have rebuilt 6 of these engines. Whats wrong with this engine has left many people scratching their heads. Every thing that makes it a SC checks out along with compression and fuel. I would like to get a sound clip so you guys could hear this thing. Got to get this thing going for Phil.
 
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Yeah Mark a sound clip would be a good idea, i feel like an idiot not being able to get this thing running, it would make me feel better if others heard what this car sounds like. Hopefully things will get workin soon.
Phil
 
i had a 1996 v6 lx rebuilt and the guys left a rag int eh oil pan. guess what, that did pretty much waht your describing. car didnt run for crap would start and chug and id floor it for fuel and it would die anyway the only way we figured it out was i got pissed and took a saw to my oil filter, filled with threads. has the bottm end been rebuilt? and before you asked i had the engine rebuilt cuz i blew the head gaskets cuz i drove it like tiw was an sc ahhaha :D
 
Mark, I may come by and lend a hand. I checked a lot out with phil earlier on in the year. I was thinking maybe faulty wiring between the ecu, and the other related parts. The injectors all ohm out correctly, the tps/iac were from my 94, know they were good. My only thought would be to use a meter at the ecu plug and see what the readings are there vs the readings at their correlating sensors/devices. The whole rag in the engine sounds a tad odd, but i've seen stranger things. I can stop over after work tomorrow for a lil bit, but I gotta get my 95 back together for the bash, and my sis's car back together before I go to the bash. Gimme a call, let me know if its all ok to swing on by.
 
pearl95sc said:
The whole rag in the engine sounds a tad odd, but i've seen stranger things.
yeah the rag is odd but i gotta tell you i wouldnt have believed it if i hadnt seen it the guys who do the work at the shop actually (come to find out later) botched an oil change and fluids check by leaving the radiator EMPTY!!!! the kid blew his engine. my car hasnt gone back
 
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