96 Lasabre sensor problem

[vair guy]

This car runs great 95% of the time. The other 5% not so good. I've got this intermittent problem I will describe. The throttle pedal starts to stick (I mean stick bad), engine runs rough, sometimes dies out (if it dies its very hard to start), and a terribly rotten smell usually goes along with it. My code readouts are P0107 P0108 and P1406. From what I can see (from looking around on the internet) it appears that these codes usually indicate a bad MAP sensor. I'm thinking its the TPS because of the sticky pedal. I think the throttle shaft goes straight into the TPS. If I had cash to spare I'd just buy both of them but I'm on a tight budget. I realize I could probably figure it out by putting a voltmeter on either one and check it when it fails. Trouble is it's intermittent and I need to have to have this car running ok as soon as possible. What do you expert dudes think?

[Blue Bowtie]

Before you replace anything, get some carb/throttle body cleaner in a spray can. Remove the air intake bellows from the TB. Clean the throttle plate both front and back, and the pivots from inside the TB. Try directing a little cleaner via the straw/tube attachment into the idle air control openings. Make sure the cable is not binding, and try it again.

[Tech II]

I agree with Blue.....think the throttle plate is sticking in the bore...

[HotZ28]

Remove MAF before spraying carb cleaner into the T/B. In addition, remove IAC and clean pintle & seat with carb cleaner & Q-tips.

[vair guy]

OK I'll give that a try but I have to ask a question. How would a sticky throttle plate make my car die out and run like crap?

[Tech II]

We want you to clean the throttle plate and bore, because that could be your sticking pedal problem......if it was really bad, and the gas pedal was released quickly, and it slammed shut, it could cut off the air before the IAC could compensate(?).....that's another reason why we want you to remove the IAC and clean, not only the pintle, but the bore that it mates with....

Did you have the codes cleared, and the see which one returned?

[Blue Bowtie]

HotZ - Good catch on the MAF. Those aren't cheap. The only potential problem is the screws sticking/seizing in the TB and breaking off. That can be repaired, but it's a PITA. Same with the IAC. Yes, I've broken off both of them in older cars. No fun. I just though he could "cheat" a little and try cleaning without removal first.

Cleaning the entire unit would be good. My thinking was that the bore/plate is so bad that just cleaning the plate would solve most of the symptoms and prove that he doesn't need to replace an entire array of sensors needlessly. I suspect the IAC is at least partially functional since there was no mention of wild startup idle issues.

Tech II is correct. Not only would a sticking plate make it really tough for the IAC to keep up with demand from rapid changes but it would make the presumed closed throttle position TPS voltage vary all over the map, creating mind-bending havoc for the PCM to try to guess at injector pulse width, timing, EGR function, and IAC position.