Bad Driveability Problem
Thread Starter
Advanced
Joined: Nov 2004
Posts: 79
Likes: 0
From: Richmond VA
Bad Driveability Problem
I have an 87 A4 that is stock accept for empty cats. The car has had difficulty starting when cold. As it warms up, the motor smooths out. Recently, a new problem reared up: once at regular operating temp (195-205 for my car) the car losses power and the SES light turns on. In this state, the car will not rev with more that 1/4 throttle and stuggles to pull past 2000 rpm. After sitting and cooling for a few munites, the problem goes away only to return as soon as the car is at normal operating temp.
The computer said bad MAF and TPS - both of which I replaced. I have also cleaned the K&N air filter, changed the fuel filter, dist cap & rotor, ignition control module, and spark plug wires and fixed a very small vacuum leak.
Does anyone have any ideas? Could EGR or the FPR cause a problem like this?
Thanks,
Phillip
The computer said bad MAF and TPS - both of which I replaced. I have also cleaned the K&N air filter, changed the fuel filter, dist cap & rotor, ignition control module, and spark plug wires and fixed a very small vacuum leak.
Does anyone have any ideas? Could EGR or the FPR cause a problem like this?
Thanks,
Phillip
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
EGR won't. FPR would do it all the time.
Did you replace the MAF relays?
To me, it's heat related... which makes be suspect something in the engine harness.
The earlier C4s have a rather gnarly engine harness. The wiring does not deal well with heat and over time, the insulation will crack, peal, chaffe, scuff... take your pick. And all of that equals one thing - dead shorts.
I would check the wiring and make sure you are getting good connections between the sensors and the ECM.
There is also a chance that the ECM is failing. But since it's inside the car, external heat may not be the issue, but internal heat - a chip is failing. The next time this happens, try some cold spray on the chips in the ECM and see what happens.
It could also be a failing fuel pump. Infact, that is my favourite... they fail as they heat up... and heating is all linear.
So is cooling.
I would put a fuel pressure gauge on it and see what happens.
Did you replace the MAF relays?
To me, it's heat related... which makes be suspect something in the engine harness.
The earlier C4s have a rather gnarly engine harness. The wiring does not deal well with heat and over time, the insulation will crack, peal, chaffe, scuff... take your pick. And all of that equals one thing - dead shorts.
I would check the wiring and make sure you are getting good connections between the sensors and the ECM.
There is also a chance that the ECM is failing. But since it's inside the car, external heat may not be the issue, but internal heat - a chip is failing. The next time this happens, try some cold spray on the chips in the ECM and see what happens.
It could also be a failing fuel pump. Infact, that is my favourite... they fail as they heat up... and heating is all linear.
So is cooling.
I would put a fuel pressure gauge on it and see what happens.
Racer
Joined: May 2006
Posts: 293
Likes: 0
Originally Posted by Former Ford Boy
The computer said bad MAF and TPS - both of which I replaced.
Thanks,
Phillip
Thanks,
Phillip
