Hello everybody. I have a question about my engine. I just turned her over and had it running for the first time yesterday. Everything was going good, until I went to adjust the timing to the proper alignment. Now, even when I put the cam angle sensor back to where I began, it revs up to about 2,800rpm, stays steady then slowly climps steadily from there, and then if I where to let it, it would probably keep going higher. Throttle is closed, and here are some things I have double and even triple checked: Both vsv's connections and vacuum lines, all other vacuum lines, idle speed valve on the manifold, checked the cps alignment, checked the cold start injector, checked for boost leaks, checked all electrical connections. Still does it. External things I have done: K&N filter to adapter on the meter, titan downpipe, msd wires, stainless steel accordian pipe, nothing else that really affects the engine operation. I did take the sensor off of the afm to clean it, and the inside of the afm with soap and water, don't know if that would have damaged the empty tube. I have run out of things to check now. She does run good though! Well, any suggestions would be cool. Oh, if nobody remembers, I have a 89 7mgte.
You sure you have no leaks after the throttle plate, and that the plate is really closed? Throttle position sensor adjusted correctly? idle controller working correctly? Any codes?
The AFM is rarely a fan of being cleaned, but usually causes it to fail, not read incorrectly. That said, see if you can find someone with a spare and try it out.
Yeah, I did find that out afterwords. The good part about the cleaning though is I didn't use any solvent, I just wiped it off with paper towel. I have checked the idle sensor and throttle position senensor for operation. I don't have a diagnostic tool, and the car is not drivable. As it revs, you can tap the gas and it cuts out for a second and then resumes. Also, the closer I move it to 12 degrees, it revs even higher. Unfortunately, I talked to my engine guy about my head when I took it in to get it decked. He said that he cleaned up my valves and the guides with a soft brush and some sort of solvent; but then he told me something that kind of pissed me off..... he said he did a 8 second valve grind on each valve with light grit. If I'm thinking right, this is probably what is causing my idle problem. So, if this is the case, I will have to pull everything apart and take the head in again, and probably spend about 1,000 that I wanted to wait to do later.....but I don't know yet if thats it.
I dont have access to a spare maf, but I think this could also be the culprit. I cleaned it now with maf sensor cleaner, and the engine was running fine. After about 5 minutes, it started all over again. I think that it is junk.
tapping the gas and a cut out is a symptom of not having the AFM working or plugged in. For a diagnostic tool, if you can find a paper clip and have the key, you have the tool. Jumper e1 and b1 in the diag block and turn the car to the on position but don't start it and you're in business...just read the flashes of the CEL and compare them to the manual.
I would seriously doubt the valves are a problem. The quick grind was likely just removing some accumulated carbon and soot so they would seat a little better.
I was hoping that wouldn't be the problem. I can tell its some sort of a sensor issue the way it idles erratically. Thanks for the info, I am going to try that out! I really think its the AFM.
Well, its throwing up a code 51, which is a switch condition signal. It also was giving me a oxy sensor issue, which I guessed would be the case. I dont have my a/c hooked up, but I don't think that would cause the abnormal rpms. It says it might be the throttle position sensor, but that is still set from factory. I still think its the afm or the idle control valve. Its also giving me a code 41 now, which is indeed the throttle position sensor. I will attempt to adjust it.
Last edited by SupraTuned; 05-18-2009 at 03:59 PM.
as for the cut out, my buddy had that same problem, if idle held between 2000-3000 it would cut in and out and it turned out that the tps was set wrong (even tho he didnt change it, still got knocked out of place) and his IACV was bad, althought the AFM is deffinatly still up there on the top 3, as for the oxy sensor that causes a lean or rich code ive never seen one caus a rpm problem as well as the A/C wouldent caus that either accept for the exception of at normal idle possibly being a little lower due to the motor not haveing to rotate the compressor so it doseent work as hard.
Thanks for the input! I checked all that stuff, and it actually ended up being the idle speed control valve. It just wasn't actuating properly. It tested bad, and of course when I replaced it with a different one to check it ran awesome.
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