Ok, here's the deal. I have an '86 IROC 305 TPI that I just bought. Finally getting around to checking codes, etc. Jumping the two pins, I got a code 34 (MAF). After fixing a split in the ductwork between the MAF sensor and the TB, still gave the code. Cleaned the MAF with electric cleaner, but still no luck. I decided to take it to my mechanic since I do know someone who will take care of me and I knew I would just have to start replacing stuff at a cost of big $$$. Plus those scanners can give 50x the info than can be gotten from just reading the codes. Anyway, these were my symptoms. Crappy rough idle, car trying to die at idle, cooling fan did not come on, check engine light. Previous owner had been poking around and trying to fix the problem, too, as could be seen the further we dug into this. One thing was previous owner had put a manually controlled fan on it 'cause he couldn't get the computer to engage the factory fan (although in diagonistic mode, the fan still came on). I could also see someone had been poking around the MAF sensor and relays. After I got a code 34, I unplugged the MAF and got a code 33 as someone had suggested that would tell me that my MAF is bad. WRONG. (more on that later) When we plugged in the scanner, it would not read and kept saying communication could not be established. After a while of this crap, we ordered a new computer and sure 'nuff, the computer was shot (one down, many to go). New computer gave the scanner a code 34, still though. Ordered a new MAF and plugged it in, still got a code 34. So we started checking relays and realized the MAF power relay was not sending power out to the MAF sensor. We replaced that relay, which fixed that problem. Checked codes again and now we got a code 36???, if I remember correctly, anyway, it was the code for MAF burnoff relay and was easily fixed due to bad connection in the plug of the MAF burnoff relay. Time to check codes again. Yea, now we get a code 27, Manifold Air Temperature sensor. I didn't even know I had one of those. Sure enough, scanner showed a MAT of 32* F. Found the MAT, unplugged it and plugged into a new one, which fixed the problem (too bad I will have to unbolt the intake runners to put install the new sensor into the plenum). What had happened here was that the connector had deteriorated and the plastic in the plug had broken off in the sensor receptacle. Finally, no codes and the damn thing will idle again. Letting the temp rise now engages the factory fan, and I assume this was due the problem in the computer. Hope this will help someone with the common code 34. All this was cheaper than the cost of a new MAF sensor, which we sent back. ECM was about $70 and about $35 more for MAF power relay, new MAT sensor, and MAT wiring harness.

 

Yeah... Took me a while to figure out my computer was bad... well the dealer figured that out... I told them to take it out for a ride and pay attention to the TPS voltage at WOT... and that was the problem... but it was the ECM and not the sensor. Feels great to find the problem eh?

Oh.. and you don't have to take the runners off.. jsut the plenum.. You just pull the plenum off with a considerable amount of foce, cause the gaskets stick to both surfaces.

 

I haven't taken it off before, but it looks like if I don't tear the gaskets, then it should be easy. If they do tear, it might be a great time for some portin' and polishin'!

 

They will most likely tear.... you should pick up new gaskets anyway.... factory gaskets from the dealer is the best bet.. they are nice and beefy, with the plastic tabs so you don't have to fight withthe gasket to align it

 

After everything was fixed and no codes, idle was still fluctuating and comin close to stalling. After cleaning the black crap out of the throttle body walls (thin thin black film) car idled normally. I couldn't believe this coating would cause make such a dramatic difference, but it did.