Recently had the stock exhaust on my AUI 5.0L replaced with pacemakers, x-pipe, lukey muffs, twin 2 1/4" pipes, no rear resonator and two baffled stainless tips (sound fantastic from outside but despite fitting additional sound-proofing matting in boot it's still a bit loud and has a drone from inside the cabin - still trying to work that one out). Also fitted a K&N filter.
Noticable power gain however the engine won't settle on a consistent rev when cruising (cruise off or on) or on a gentle incline... the engine seems to start this rythmic rev surge. Not so bad that you can feel real a change in pace or notice the needle on the tacho move much but definately there in the audio department. It's driving me nuts!
Surely this can't be normal. I've tried resetting the computer and going through the full re-learn process but this hasn't made any difference.
I don't know whether this is a transmission issue or is because of the new exhaust or maybe something else.
Should I be putting a rear resonator (twin chamber) back on?
At 80km/h, my car always changes between different gears but that is normal. The auto is obviously meant to switch back at forth...
I am thinking that maybe you should have the MAF sensor and idle speed controller cleaned. It is a common problem to have the car rev around a bit because these two are dirty. Can she hold rev when she is at idle at all?
I am not exactly sure if this will fix your problem but it is a start and it certainly doesn't hurt to clean both of these out.
The EF's were renowned for "hunting" gears, but theoretically this was sorted in the EL, and shouldn't be an issue in the AU (with new box and all).
Might be worth checking the TPS, although it would be freaky for it to die at the same time. Another thought would be the hego sensor - since that would have been removed etc with the new exhaust. Also, some silicon sealants that some places use on exhausts can kill the sensors. This *could* be it trying to alter mixtures with a slow responding sensor . . .
Would this silicon actually kill the sensors or just knock them around for a short while?
My brother (bless his soul) did find the air temp sensor disconnected and hanging down in the engine bay 2 or 3 days after the system was changed... fools at exhaust place didn't re-connect. Could this have caused an ongoing problem?
Seems to idle OK... wavers a little but has always done that a little. I'll try it in neutral at 1800 to 2000 revs (my usual at speed rev range - assume all are) and see what it does.
Would this silicon actually kill the sensors or just knock them around for a short while?
My brother (bless his soul) did find the air temp sensor disconnected and hanging down in the engine bay 2 or 3 days after the system was changed... fools at exhaust place didn't re-connect. Could this have caused an ongoing problem?
Seems to idle OK... wavers a little but has always done that a little. I'll try it in neutral at 1800 to 2000 revs (my usual at speed rev range - assume all are) and see what it does.
Yes that would not help it at all, since the air temp is now connected again, may pay to reset the computer again and let it learn with the extra input.
Jason
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I did put something here, but it vanshied, I think
Yes that would not help it at all, since the air temp is now connected again, may pay to reset the computer again and let it learn with the extra input.
I did a full reset a few days after sensor was put back in.
I guess it would pay to check the sensor though as bouncing around the engine bay may have damaged it. Suprised it wasn't melted on the extractors (no burn marks or melting evident).
With the new K&N filter, some residual oil may have been sucked off the filter and may now be coating the MAF sensor wire causing incorrect readings.
Wouldnt hurt to clean the wire anyway, spraying it carefully with carby cleaner...probably never been done in the cars life.
^^^ Good suggestion (worthwhile doing even if the car was running fairly well).
If it is the wrong silicon, I'm fairly sure the sensor will be dead.
But probably your best first stop would be to see if the car is throwing any error codes (might tell you straight out whats wrong).
Not sure what the procedure is on an AU, but its not too hard on the EL's. There might be a post about it (try a search), or someone might post a how-to.
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