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Brad

'96 1.8 Dx 420K Miles Carbon Carbon And More Carbon!

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I'm sure this issue has been addressed in the past but cannot find a readily available thread to review. Please offer your thoughts. Understand I am NOT tech savvy when it comes to car repairs. But if I can do some troubleshooting on my own I will gladly invite your expertise on the matter. TIA

 

I believe my issue began a few years back with high oil consumption. I just chalked it up to age and added a quart every 6-8 weeks. Recently it dropped to running through 3-4 quarts a month. Along with it came the CEL indicating P0171 too lean in bank one. I had horrible acceleration and sputtering. Due to my schedule I had to endure this about a month before I was able to get over to my mechanic. He first replaced the fuel filter as it was clogged. No change. Then he got under the back seat and replaced the fuel pump. That appears to have done the trick as all acceleration was back and no CEL.

 

I got about miles down the road and here comes a skip, a sputter, and the CEL again. I checked it with my cheap OBD and it revealed P0401 EGR Flow. I called my mechanic and asked if anything he did on the fuel pump and testing vacuum lines would have tripped this code. He said no. Again, a busy schedule and I monitored it. Each day I would fire it up no problem. She runs beautifully for the first 4-5 minutes. No skipping or popping at high speeds. But when I slow down to the 30-40 range, it starts popping and skipping like crazy. It has been progressively getting worse for the past two weeks.

 

After researching online I decided to pick up a new EGR as it had never been replaced. I got to my mechanic yesterday and he did a cleaning on the intakes and EGR. He said they were caked with carbon bad. I got back in and drove about 5 miles and it starts all over again. I went back to him and he pulled the EGR and it was completely full of carbon again...he just cleaned it!

 

He popped on the new EGR and it made absolutely no difference. In doing so, he discovered a split in the rubber hose going from the EGR to the modulator. Replaced it. No difference.

This is the best video I can find that addresses my issue. I'm curious now from watching it if the VSV solenoid has gone bad? Should I test/replace? Wouldn't I have gotten an 0406 code for the VSV rather than the 0401 for EGR?



My mechanic says the next step is to clean all the lines which likely needs to be done to get carbon free.

I frankly am still at a loss how this issue popped up with no resolution the precise instant the lean fuel bank issue was resolved with a new fuel pump.

 

Thanks again for any help!

One last thing. My mechanic thinks he resolved the oil issue when he found oil all over the engine. All of the manifold bolts were loose. He tightened them down to restore the gasket and all seems ok now with no oil loss in 4 weeks.

Edited by Brad

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I believe my issue began a few years back with high oil consumption. I just chalked it up to age and added a quart every 6-8 weeks. Recently it dropped to running through 3-4 quarts a month.

One last thing. My mechanic thinks he resolved the oil issue when he found oil all over the engine. All of the manifold bolts were loose. He tightened them down to restore the gasket and all seems ok now with no oil loss in 4 weeks.

 

There's your problem... Severe oil consumption.

 

No oil can leak at intake manifold or exhaust manifold.

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The engine computer doesn't monitor EGR if there's any air/fuel ratio faults (like running lean) as it needs the engine running correctly to monitor if the EGR is working or not. Likely the EGR was not working properly for quite some time but the computer was unable to flag it because the engine was running lean so it couldn't monitor it. He'll need to bore the carbon out of the port on the cylinder head and pull the throttle body off and clean the carbon from the intake manifold. For boring the head I suggest some thick steel cable with the end cut and frayed slightly and chucked in a drill, it'll wire brush out the passage and make it perfectly clean, any left over carbon will give new carbon a place to stick and build back up. He may need a long drill bit to get through if it's packed solid, a quick test is to take the EGR tube off the head and start the car, it should blow exhaust out the port, if none comes out then it's clogged up solid. Typically the valve itself and the modulator disc are what fails in addition to there being a clog, but you can't test the valve and modulator entirely until the passages are unclogged.

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this thread is doing the thing where it'll load in a loop and then not show the last reply till I begin to type a reply or post a reply, so strange!

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Thanks Overdrive...

 

You seem to have the solution. I will know tomorrow and be back with what my mechanic finds.

 

Thx

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