Strange problems

Gerry Rider

Registered User
I just finished installing new valve cover gaskets and a new power steering pump, with all the needed teardown to do it. Now engine idles like crap, sounds like a fuel dragster. RPM's go up to 2 or 3000 and then down all by themselves. Finally homing in on a very stumbling idle of 500 to 1000. I put on a new TPS on the 75mm throttle body which had been working great. This helped a little, but still pretty bad idle. Exhaust also has a very strange smell, not sure it's a too rich smell, just very chemical odor. Above idle car runs great, smooth with lots of kick. Anyone have any suggestions --bigger T/B not good, bad IAC, catalytic converter failure, O2 sensor failure, what ???????
Gerry
 
when i did the motor swap this week end i had the same problem. it was a vac leak on the intake to intake manfold. had to take it off and reRVT it to get it to seal right. it you can find a vac leak then it would try the IAC
 
Don't think it's a vacuum leak, at least a significant one. When I pull the connector from the IAC, the engine quits. If there was a leak, the engine would stay running. Could well be a bad IAC though. When I put things back together, I crossed up 2 plug wires. It backfired a couple of times before I got it shut off. Could this ruin either the O2 sensors or the CATS, and this is the problem? I'll have to find an IAC to try it.
Gerry
 
Arent our TPS adjustable? Perhaps you knocked it out of spec - I know on my RX7 you move in one cm too far and it started hunting idle wise BAD...
 
im beting on the IAC. that is where i would start. did you pull codes? are you getin O2 codes?
 
The TPS is adjustable. I set it at .95volts per spec. Still hunts. I too think the IAC is bad. Can't get one locally, but will order new one today.
Gerry
 
I pulled codes today and got 11,41 and 91. 11 says all OK while 41 and 91 are HEGO codes, which are 02 related and say that it's lean. The leaness might account for the chemical smell of the exhaust, and could be tied to the IAC. I ordered a new one from RockAuto today. Any more thoughts on these codes?
Gerry
 
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just to ask have you checked thr O2 conections? but i dout both right bank(41) and left bank(91) are bad or loose
 
Wires are on right now

123456 or 123465 ?

If you don't understand the question... I can assure you they're wrong. :cool:

If you understand the question, then no need to respond.. then I'd highly recommend you reseal your IC tubes especially the top rear joint where the lower tube meets the plenum.
 
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123465

Installed new IAC today, improved the idle some, but still idles quite poorly.
On the road, it runs the best it's ever run. The 75mm T/B is obviously allowing a supply of air closer to what the blower wants to have. I use the teflon seals on the I/C tubes. I think they are all sealed, but I will make certain tomorrow. The new IAC also seems to have taken care of the KOEO codes because all the pulls is Code 11. With engine running however I get 41, 91, 72, 73, 74 and 25. This, I think says it's still running too lean. If the I/c tube seals check out OK tomorrow, I think I'll reinstall the stock T/B and see if the poor idle goes away.
Gerry
 
strange problems

Tried something today, -- rotated the MAF while engine idled. Rotating it about 30 degrees smoothed out the idle some. Then tried tilting it up and down as far as the silicone couplings would allow. Tilting the rear of MAF up also made a small improvement. All this seems to indicate that the higher inlet flow allowed by the 75 mm T/B and the MAC CAI with the upstream bend is screwing up the sensing by the stock MAF at idle. Higher RPM's seem fine. I removed the MAF screen and cleaned the MAF with solvent. With all this, the idle is now relatively stable, mean sounding, but stable for a lengthy time sitting running.
Gerry
 
Sorry to side track your thread. You said you installed new teflon gaskets on the I/C tubes. Do you feel that they are sealed? Reason I'm asking I just bought a set off E-bay - VBaileyent1 looking at them with my son I feel they are too stiff to conform to the bevelled edges of the tubes and wonder if they will work. I have not installed them yet. Did you get yours gaskets from the same seller?
 
I got my teflon gaskets from a nice guy on the SC site from Texas. I've had them apart and resealed them 7 or 8 times and they still seem to seal well.
Gerry
 
Have you set up the TB stop screw and the IAC bypass properly?

One sign of it not being correct is the fact the car stalled when you unplugged the IAC. This means the IAC is probably close to max duty cycle trying to keep the car running.

Set the TB stop screw per spec for that TB, then don't touch it after. You may need someone's help to keep the car running, but unplug the IAC and start the car. Let it idle down and open up the IAC bypass screw until the car can idle on its own at around 550 rpm's. Confirm this several times by shutting the car off and restarting it. When satisfied, then shut the car off and plug the IAC back in. Start up and you should idle at around 650 to 700.

Frit
 
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