2 engine questions

[pandorasboyfriend]

1) My wife has a 95 TA A4. The car runs good till you get it up to 4500 RPM,

then it back fires through the throttle body. It sounds like the optispark. I was

wondering if the optispark goes bad, will the service engine light come on? Hers does not.


2) Ok my car is a 95 TA A4 as well. It runs like a champ until it gets warmed up,

then it doesn't want to go anywhere. Like it's running on 4 four cylinders. I

mean it really is that bad. I'm thinking bad head. Anyone else had this problem?

thanks, PB

[Injuneer]

1) My wife has a 95 TA A4. The car runs good till you get it up to 4500 RPM,

then it back fires through the throttle body. It sounds like the optispark. I was

wondering if the optispark goes bad, will the service engine light come on? Hers does not.

The Opti has two distinct parts. If the optical sensor is failing, or the wires from the optical section are corroded, you will get DTC codes for loss of high and low resolution pulse failures. SES light should be on, when they are active. The other part of the Opti is the cap and rotor. If that is failing, there will be no codes set in the OBD-I cars (93-95). In the later models, you will get misfire codes, but not Opti specific codes.

2) Ok my car is a 95 TA A4 as well. It runs like a champ until it gets warmed up,

then it doesn't want to go anywhere. Like it's running on 4 four cylinders. I

mean it really is that bad. I'm thinking bad head. Anyone else had this problem?

thanks, PB

It something that's sensitive to heat. There are a couple of ignition components that will cause heat related problems, including the Opti optical module, the IC module, the coil and wire insulation. Could also be related to the O2 sensors and the closed loop control system.

How soon after startup does it start to run poorly?

[Joe 1320]

how many miles does each vehicle have? As Fred pointed out, it could be the opti, it could be simply plugs and wires. When the opti started going out on my 97, there were no codes. With the syptoms you describe the first thing to check is the ignition and control. If that is sound, next is fuel.

[pandorasboyfriend]

The Opti has two distinct parts. If the optical sensor is failing, or the wires from the optical section are corroded, you will get DTC codes for loss of high and low resolution pulse failures. SES light should be on, when they are active. The other part of the Opti is the cap and rotor. If that is failing, there will be no codes set in the OBD-I cars (93-95). In the later models, you will get misfire codes, but not Opti specific codes.

Both cars have OBD-II and they are 95's wierd huh? Would that make it a '96?



It something that's sensitive to heat. There are a couple of ignition components that will cause heat related problems, including the Opti optical module, the IC module, the coil and wire insulation. Could also be related to the O2 sensors and the closed loop control system.

How soon after startup does it start to run poorly?

If it's freezing outside, the car will run great all day. Since summertime has

come around it's acting up when it gets warm. To answer your question, it

acts up at 180 degrees according to the temp gauge. Here's another thing

that Joe probably needs to know as well. I removed the cat-converter and

replaced it with a straight pipe. The O2 sensors have never been changed. I

have a Borla exhaust cat back. Stock exhaust manifold. Replaced optispark

10,000 miles ago before the car sat up for 4 four years in Texas bad weather.

But like I said no codes are triggered.

[pandorasboyfriend]

how many miles does each vehicle have? As Fred pointed out, it could be the opti, it could be simply plugs and wires. When the opti started going out on my 97, there were no codes. With the syptoms you describe the first thing to check is the ignition and control. If that is sound, next is fuel.

My wifes car (car #1) has 117,000+

My car (Car#2) has 101,000+

My car, has new plugs but the wires have never been changed so you might

be onto something there. The ingition was replaced 10,000 miles ago at a

dealership so that's ok. Fuel? I have a fuel preasure tester. Do you know what

reading should be by chance?

[Joe 1320]

Since summertime has

come around it's acting up when it gets warm. To answer your question, it

acts up at 180 degrees according to the temp gauge. .

If the wires haven't been replaced, that needs to be done before you start chasing anything else. The resistance in the wires climbs as they get hot, causing all kinds of ineffecient combustion events.... read: runs like crap.
The plugs, wires and other ignition parts affect eveything else.

Fuel pressure 40-44 psi idle and it shouldn't drop under load.

[pandorasboyfriend]

Then thats where i'll start. Thanks for the help!