Well, i've been battling with the code 33/36 problem for a long time now. I believe its the code for "high voltage at the mass air flow sensor" and "burn off relay or circut something something"....I had this area's best mechanic AND the guy who taught him everything he knows working on this car for 4 days. So for anyone having a problem with this code(s), the results are as follows: the mass air flow sensor MUST BE EITHER A REBUILT BOSCH UNIT OR A FACTORY MASS AIR SENSOR. The dealer would want $580 for this piece, but I found that NAPA stocks bosch rebuilts for $180 i believe...and its a perfect match - internally, and externally...it was a Bosch unit. DO NOT buy any MAFS that is not a Bosch unit....the reason being is that the insides are different...Advance Auto Parts stocks an aftermarket MAFS made by Microtech....however, when compared to the Bosch unit, they are totally different internally. The aftermarket unit is JUNK...inside, its nothing more than a circut board with circuts on it....if you look at the Bosch unit, it has a round cave-like thing, and inside that are 4 points where an extremely thin wire loops around each point...thats the burn-off wire which is at a constatnt temperature. There are also heat-sinks on the Bosch unit. The aftermarket sensor does not have any of these - which would explain why the Snap-on diagnostics computer would throw an error code for "mass air burn off." The two look nothing alike.

In working out the bugs for this problem, the mechanics and I decided to check/replace all relays associated with the MAFS as well, which we found to be faulty. Another thing to consider is the harness that plugs into the mass air sensor....this could also be faulty, and as a precaution, i ordered a new one from the dealer and replaced the old one - because at one time, this made the values on the diagnostics computer change when it was wiggled. We also found ONE wire loose on the ECM harness....it was comming out of the harness actually....we fixed this as well, which helped the situation. After all this, I personally also reccomend that a factory rebuilt ECM be used instead of an aftermarket GP Sorenson or some other junk like that. The reason being is that we pulled a factory refurbished AC Delco ECM out of a 91 2.5L Blazer, changed proms, and the car idled, ran and started perfectly, like a new car. With the aftermarket ECM(the second one that i had gotten from the store b/c the first one was faulty too), the car cranked 15 times before it started. The Delco one only cranks maybe 2-3 times, and makes the car perform, idle and act like it should.

I dont know if many of you guys out there have this problem with your 700R4's, where the RPM's drop down ALOT and the car either stalls if you dont give it gas, or sounds like it wants to, till the RPM's make up for the gear change when you shift into reverse or drive....but we researched this topic intensely, and concluded that the IAC motor is something to obviously check/replace first.....but also, you have to set the minimmum air on the left side(drivers side) of the TPI unit (if you have TPI)....if that doesnt work, the next step would be to look at your nuetral/safety switch....located in the center console under the shift plate(on atuos only).....its a semi-circle looking thing, with a nub that slides back and forth depending on what gear you're in. What should happen, is if you get a volt meter, drop the computer, find the wire that connects from that to the computer(via wiring diagrams), you should find i believe an orange wire with a black strip in the harness going to the back of the computer...put the voltmeter needle into that "socket", and i think set the voltmeter to 20....and i believe in nuetral and park, the voltmeter should read 0.00....and when you put it in reverse, if its working correctly, its over 12.00...more like 13.69 or something....if that doesnt show up when putting it in reverse or drive(the high numbers), then that piece is faulty, which means your car will want to stall or will stall when putting it in reverse or drive...because thats what fixed the problem with me.

Other than that, just be sure to properly set the TPS and the miniumm air on the throttle body....when all is said and done, the results are amazing...my car never ran this good....it now runs and starts like a raped ape. I hope this information helps everyone out whos got these sort of problems with their cars.

Edit: Forgot to mention a few things:
-Reset/check timing
-Use the updated chip for your ECM
-Make sure everything is grounded properly
-Make sure you have no vacumn leaks

 

oh man! who u take it too.. cuz take mine to get all that done.. im have'n the same problem since it's been getting cold this fall.. which all relays u replace.. power. fuel. burn-off(that same as power just a 2nd one?) and did u have to order ur $180 Bosch MAF?

 

i ment.. did u have 2 order and how long it take.. i got to jummpy cuz i seen answers to my new problem w/ my IROC

 

I know a guy up here who works out of his garage @ his house, but has all the equipment...him and his buddy used to work for the dealerships around Northeastern PA....and whenever the dealers couldnt figure out a problem with the cars, they sent those oddball jobs to these two....so they know their s**t. Anyway, to answer your questions.....i replaced EVERY relay for the mass air sensor....there are two on the firewall and i believe i even replaced the one by the charcoal canister, b/c that made a difference too. I think the one by the canister is the burnoff relay, and the other two are power....but i'm not 100% sure...those guys knew what they were doing and they did it right. The relays however all look alike...i'm not 100% sure what is different about them other than they have different functions. I didnt replace the fuel pump relay.

The Bosch MAFS I got though NAPA....I know a guy down there that my mechanic deals with constantly....he can find anything in about an hour's time if not sooner...occaisionally, he might take a day. He got me a REMANUFACTURED Bosch MAFS for 147 bucks....thats the mechanic's cost though. I dont care what brand name it is(b/c there is a sticker on the flat outside part of the MAFS), but you peel that sticker back and you see that its a Bosch MAFS....the internals are EXACTLY to the T like those that came in our cars from the factory. This cost me $317 dollars total for all the parts I got. Hope this helps, and I hope that more poeple can benefit from this post...

EDIT: Where are you located in PA??

 

Schuylkill County. Pottsville area. so if i ask a GM Dealer that i need a Burn-off Relay they'll know what im talk'n about and not say.. oh oh its not on the computer. (autozone, advanced)

 

Not sure what makes you think the difference in design has to do with the function.

Anyway, plenty of people use that style MAF with no problems. Its just a different sensing element, one thats used on the newer than thirdgen MAF designs. I might add its a better design than the heated wire. Just do a search on the Wells MAF if you want to know more.

 

Yes, the GM dealer should know what you are talking about. I'm not sure how far Pottsville is from the Scranton area.

From going through not one, but two MAFS from Advance Auto Parts since this past March, it makes me think that the quality of the parts and the internals dont work as they should when compared the the Bosch. My mechanic obviously thinks the same, b/c that element is not present in the MAFS bought from Advance...there is no burn-off wire....its a circut board....I dont see how they could function the same, but maybe they can....I just havent had any luck with them whatsoever since this whole fiasco started......then I plug in a remanufactured Bosch....and presto.....everything works as if the car was new....how come?? Before that, the diagnostics computer kept spitting out code 33 and 36...two MAFS in a row from Advance were defective....that were brand new? Maybe...but it makes me think more about the design since the first try i had with the reman Bosch worked perfectly and since then, the car has been running the way it should. Maybe other manufactuers have good MAFS...but if i ever need one again, I'm going with the reman Bosch...now that the car is running right, and with all the mods, there is alot more power thats been restored.

EDIT: Once we set everything else on the car, we disconnected the MAFS, and the car actually ran BETTER without it connected than it did WITH it connected....that was the last thing we did before we installed the reman Bosch unit....then it ran perfect...go figure...

 

Depends how fast ya drive..like an 1:30 to 1:45hrs. I think Hanover High School is near there. we played there in October

 

and thanks man for haveing the same problem that just started w/ my IROC.. thanks a bunch..

 

....um, you're welcome? I not only had the problem, but this is the solution we came up with, thats why i'm posting my findings....I just want to help as many people as possible that may be suffering with the same symptoms.

EDIT: Its up to you if you want me to refer you to my mechanic....he's in the Waverly area which isnt far from me....

 

thats alright man.. its pretty far away for a limping IROC

 

Dont know what you've done so far to fix your car, but before you condemn the MAF sensor, do yourself a favor and replace the relays first. Too many people replace the MAF when its not needed. Sometimes the pins on the MAF get bent too, and sometimes the wires get damaged.

 

I agree also....go the cheap route first....check all relays, wires, connectors, etc....thats how I went about it....its nothing more than cheap insurance....but for me, it ended up being the ECM and the MAFS....

 

would it be bad if the TPS only had 3.60 +/- .05volts at WOT be a factor.. so codes i have are 22 and 34.. would the 22 cause the 34? Phatom TPI u think ur mechanic would know that? alright well i'll check back later.. thanks

 

He would know, but he's gone for Thanksgiving...I wont be talking to him till next monday the earliest. You mention code 22....i think we also had that code at one point during this whole thing....what is code 22 for(i dont remember)?

 

TPS.. Throttle Postion Sensor.. other side of throttle linkage.. on Throttle Body. for that sensor its 21 or 22

 

its for bad missajusted TPS. i think summ'n bout High Voltage on TPS.. or Faulty TPS

 

Oh....ok...well, we adjusted everyhting and the TPS was fine....so maybe it was that code before all the adjustments. I'm outta here...leaving for the holiday....let me know how things go if you start fixing the problem....

 

A bad TPS could throw you a MAF code, the only sure way to know is to fix it. The WOT setting on the TPS doesnt really matter all that much, though it should read a bit higher than 3.6 at WOT, should be somewhere above 4 volts. Main thing is that it has the right idle setting, and that the volts steadily increase as you open the throttle.

 

i cleared my codes when the car was warm.. and all i got now is a code 22.. so i dunno whats go'n on.. anyway.. my dad is a *****.. and i dont have ne money... we'll see