Hey! I have been having some strange problems with my 1896 TPI IROC lately. it has been sounding as if the timing is really off. and besause it is ECU controlled, i can't adjust the timing!

It backfires if i let up on the gas too fast, and the engine sounds really rough, and has no power.

I flashed the ECU and it read code "33". which according to my haynes book, means there is a problem with the "Map Sensor" or the "Manifold Absolute Pressure" sensor.

Does anyone know what this is? does anyone think this could be related to my cars poor performance?

Thanks guys!

 

One more thing, i do have a MAF sensor, im not sure if it relates to this problem or not.

 

Yes..MAP and Manifold Absolute Presure are the same thing Chris. You have a Mass Air Flow (MAF)sensor, 90 TPI and up have the MAP. You will learn to hate sensor's that measure Air Flow or pressure. Good luck..

------------------
-Red '88 IROC 5 Speed 305 TPI w/3.08
-Dual Friction Centerforce Clutch
-Accel 300+ Racing Ignition
-Accel 300+ Pro Sleeve Plug Wires
-Accel U-Grove Plugs
-Flowmaster Force II 3 Chamber Cat Back Exhaust
-Hypertech Chip
-Hypertech Airfoil
-Removed, Then Re-installed (out of fear) MAF Screens
-Gutted Air Box
-Best E/T 14.90, 60 ft. 2.17, 1/8th mile 9.61(bald tires, Code's 34,36)
-Best MPH 92.7(bald tires)

 

Goddamn, you have an iroc from 1896?!?!?! That doesnt happend to have the 15" wooden spoked wheels and the "soft top" just like the old covered wagons does it???
hehe just messing with ya, couldn't pass up being a smart *** . Good luck.

 

Thanks for the replies guys!

Well, From searching on the web, as Yarnboy said, it appears that MAPs were installed in later year camaros. I own a 1986 IROC (yes yes, withOUT the 15" wooden wheels, and 4 horse-yolk option, heh sorry about the last typo)

Problem is, is that i know My 1986 305 TPI Camaro has a MAF sensor! i removed the screens from it myself not three months ago!

A year ago, my car was running rough. It wouldn't idle, It would cough and sputter, and backfire. sometimes, when i accelerated, it would make an odd popping noise from the engine. I took my car to a shop, and they said it was the ECU.

They replaced it, and off i went!

A few days later, it acted a bit funny again, but I was out of state already. Finally, After moving here to california, a year later, My car is starting to show the same symptoms again!

I flashed my ECU and it gave me the error code "33". which is "MAP sensor bad". But like i said, i don't HAVE a map sensor! i have a MAF sensor.

When they replaced my ECU, they might have used one from a later year camaro than mine. Would this be causing my problem? Is is safe to replace a ECU with a diffrent model/year ECU? Would my original ECU have given me this code "33"?

Thanks alot guys, Without your help, i would shrivle up and die. I just move out here to california, and don't know anyone!

 

Disconnect the MAF sensor and reset the computer..If you don't know how, it's a connector over by the battery..looks just like the cooling fan connector..un plug both for about 10 seconds then plug em back in and start the car with the MAF unplugged..see if it runs better or worse..should run worse..check your codes. You should throw a 33 or a 34. Plug the MAF back in when you turn the car off..turn it on, let it idle..take a screwdriver handle and gentle tap on the MAF sensor and see if the car stumbles or respondes at all. If so I'd say your MAF is going bad. ***PUT YOUR MAF SCREENS BACK IN!!*** That free MOD is no long looked at as a performance MOD..it's more or less a cause problems an go just as fast mod. I bet you will feel a difference in how the car resonds to a light throttle touch..those scrrens actually have a purpose. I had mine out then put them back in after Vader wrote the world on why not to take them out. I'd do a search in this forum for a subject called "Vader what are your reasons for not removing the MAF screens?" Or somethin equivelent like that. it is scary. I put mine back in that night. Car run's better now..I still have my MAF sensor woes..but that's not your problem. I am done typeing..try tapping on the sensor and un plugging it. That's pretty much my diagnostic advice. good luck!

------------------
-Red '88 IROC 5 Speed 305 TPI w/3.08
-Dual Friction Centerforce Clutch
-Accel 300+ Racing Ignition
-Accel 300+ Pro Sleeve Plug Wires
-Accel U-Grove Plugs
-Flowmaster Force II 3 Chamber Cat Back Exhaust
-Hypertech Chip
-Hypertech Airfoil
-Removed, Then Re-installed (out of fear) MAF Screens
-Gutted Air Box
-Best E/T 14.90, 60 ft. 2.17, 1/8th mile 9.61(bald tires, Code's 34,36)
-Best MPH 92.7(bald tires)

 

Thanks again Yarnboy!

Im at work right now, so it makes it hard to do that this second, but in a few hours, i will try it out.

Shoot! taking the screens out is bad? darn it. I read about that "mod" on several camaro sites, i figured that it wouldn't be up if it were a bad thing. Of course i don't have the screens anymore either *slaps head*

Well, hopefully i can get this problem fixed. So you think it might be the MAF itself which is bad? Well, 400 bucks for a new one *doubles over in pain* isn't as bad as a new engine! Ill have to have my car checked out, but I do like to understand what the problem might be before i take my car to the shop.

Thanks alot for the quick responses!

 

Christos,

First, I'll spare you most of my customary lecture on removing the screens from Bosch MAF sensors. Let it suffice to say that a 305 engine almost NEVER needs more flow than the stock MAF can deliver. Unless you have a monster cam and a different TB, plenum, runners, base, and exhast, and have changed the valves to 1.94/1.60, you shouldn't need to be concerned with the MAF as a restriction. Removing the screens may have caused the inlet air flow to take a different route through the sensor body, causing the erroneous readings. There have been several other instances of this ocurring after screen removal, and you might be another of the unlucky ones.

Second, the Haynes manuals neglects to mention that DTC's can have different definitions depending upon the vehicle model, year, and control/fuel systems. If you want a complete listing for GM cars through 1992, check this link:

GM Error Codes.pdf

You'll need Adobe Acrobat Reader to open the file (see link below).

Third, a '33' on your ECM is for high MAF flow. This is usually a result of a faulty MAF, incorrectly adjusted TPS, failing MAF power relay,

Fourth, don't spend $400.00 on a replacement MAF from the dealer or anywhere else. Check out a Wells/Conrad SU-145 MAF. It will outflow the Bosch MAF and costs about $170.00 new, not rebuilt. It has a more modern thick-film sensor, a different inlet screen design, and larger body diameter. It has no heat sink in the body, and is basically a functional clone of the LT1 MAF. (Don't remove the inlet laminator from this unit!) I've had one for two years and heve had excellent results.

Finally, you can adjust the base timing on your engine. Read the manual for directions.

------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0

 

Thanks for all your help!

I had no tools really, so all i got a chance to do last night was tep the MAF while the car was running. it didn't seem to make any sound or change pitch or anything.

Still confusing, i didn't know that about the MAF, i wish i had known before i took thoes screens out. Hah! ill make sure ill ask questions here before i do anything now. hahaha.

Ended up going to the firestone up the street to have them check out my car. charges 69 bucks. hope they don't just flash the ECU for that price.

Well, if anyone cares, ill post the outcome on this message string.

Thanks again Yarnboy, for all your help!

 

One more question Yarnboy, If i do pick up that MAF you suggested, Is it a direct install for my 1986 IROC? I mean, the throttle air-body linkage (or whatever that little plactic thing is called, which goes from the airfilters to the throttlebody!)

Could i just pop the old one out and install the new one? Or will i need some other parts, or some way cutting or somethign to make it fit?

Dude, Yarnboy, If you ever come to Aliso Viejo, CA ... ill treat you to lunch! haha

 

I am not a mechanic or even a fake one..I've just had alot of problems with my MAF and read Vader's old posts very carefully. I didn't suggest a MAF..Vader did..get that one for sure if you have to replace it. Ask the place you are going to to tell you exactly what they did to come up with what ever they come up with. It is very easy for a place to charge you an hour of labor then say "replace the ecm and MAF" which is exactly what a plce here did..it's like ok thanks no problem..here's 500 bucks. It sucks...ok I am rambleing on..the MAF Vader is talking about should require no aditonal work at all..MAF removal is the easiest thing known to man. Unscrew the screw going to the TB ducting, un screw the screw going to the air filter ducting. Just so there is no confusion..the MAF is a cylindrical unit..you reaplce the whole thing..not just the little hot wire in the middle..I looks like a pastic can with a box on the bottom. good luck

------------------
-Red '88 IROC 5 Speed 305 TPI w/3.08
-Dual Friction Centerforce Clutch
-Accel 300+ Racing Ignition
-Accel 300+ Pro Sleeve Plug Wires
-Accel U-Grove Plugs
-Flowmaster Force II 3 Chamber Cat Back Exhaust
-Hypertech Chip
-Hypertech Airfoil
-Removed, Then Re-installed (out of fear) MAF Screens
-Gutted Air Box
-Best E/T 14.90, 60 ft. 2.17, 1/8th mile 9.61(bald tires, Code's 34,36)
-Best MPH 92.7(bald tires)

 

Thanks again. Just got a phonecall from firestone. they said it was the MAF! They also quoted me on a price (550.00) ouchie, thanks for the information on the other MAF! Hopefully pep boys can get it for me.

Well, They said they suspect that it's the MAF, and they also said i needed a new exhaust system. (might be part of that sound problem)

Well, Back to work!

 

Any idea where i can find the "Wells/Conrad SU-145 MAF"

is that "SU" in the name a SummitRacing product number?

Thanks again!

 

Woo! bought a new borg warner MAF today from pepboys.

Man, i can't believe how much firestone wanted to charge me for the MAF, let alone install it (80 bucks just to install it!)

Now im no smart with cars, but uh... sorry. it was too easy. took me 5 mins to install, with a friggen penny as a flathead screwdriver! haha, working at the office is cool.

Anyway, I disconnected wires like mad, and reconnected them, trying to find which one was my ECU so i could reset it. luckily, i somehow found it, and when i flashed my ECU is gave me a plain code "12". woo!

Havn't given my car the driving test yet, but ohh fingers are crossed, let me tell you. Anything to get my power back, and stop thoes backfires when i let up on the gas.

Ill post my cars status tommrow. not sure if anyone cares, but hey, someone might have a similar problem someday, and might find this whole message string usefull.

 

I care..very much so..please tell me what happens. I am bidding on a MAF sensor online..dont bid or I will kill you..heh..seriously..pleae dont..I'm poor..I'd like to know your results with the new MAF.

------------------
-Red '88 IROC 5 Speed 305 TPI w/3.08
-Dual Friction Centerforce Clutch
-Accel 300+ Racing Ignition
-Accel 300+ Pro Sleeve Plug Wires
-Accel U-Groove Plugs
-Flowmaster Force II 3 Chamber Cat Back Exhaust
-Hypertech Chip
-Hypertech Airfoil
-Removed, Then Re-installed (out of fear) MAF Screens
-Gutted Air Box
-Best E/T 14.90, 60 ft. 2.17, 1/8th mile 9.61(bald tires, Code's 34,36)
-Best MPH 92.7(bald tires)

 

No worries yarnboy, i don't plan on bidding for one! I picked up a borg warner MAF from pepboys for 220 bucks. not cheap, but a lot less expensive then 550.00 from GM!

good luck on the bidding!

ill post tommrow how my car drives.

 

well, replaced the MAF, and the car is running worse, same symptoms.

After i reset the ECU, it flashed me a code "44". lean exhaust.

oh how im learning to hate cars as much as i hae comptuers....

 

Well You know whats the worst?

cars with Computers!


arrgh!


My Ranchero Dosent have No Freaking 220.00 MAF sensor!




------------------
85 Z28 - Daily Driver
60 Ranchero - Project ( Money Hole )

 

Christos,

What MAF did you use as a replacement? A used-but-nice MAF purchased on-line may not have been so nice.

The '44' is an elusive code. The first thing to do is verify that the intake ducts are not leaking. You should also inspect the PCV system and all vacuum lines for leaks. Any additional air leaking into the intake that is not measured by the MAF will help set a '44'.

Incidentally, there are a couple of TSBs from GM regarding the '44' DTC. One is for cracks in the plastic air resonator box in front of the TB. Apparently, the ultrasonically welded seams have a tendency to fail, allowing air to leak in. The other is for a "bugged" PROM in the ECM. The replacement PROM resolves a lot of ECM issues for the '86 TPI. I found it made a significant difference in my '86. Some other advantages are a richer mid-range fuel curve, a higher TCC lockup point, higher base target idle speed, and more tolerance of varying ECM inputs.

Check the NHTSA site for details.

------------------
Later,
Vader
------------------
"Make Me Bad"
Adobe Acrobat Reader 4.0

 

Thanks for the suggestion!

Well, I bought a new MAF from pepboys (borg warner) and installed it, and flashed my ECU. my car ran worse, and shot me a code 44. i used some dielectric grease on the connecters, but still no go.

I actually ended up taking the new MAF back, and putting back in the old one. car still runs bad, but not as bad as it did with the new MAF! plus, its been a few days, and i havn't had another code flash yet!

So what was this about the ECU? i had mine replaced a year ago, when i had a similar problem, i was thinking that might be the problem now!

How much did you pay for the new ECU or PROM? do you have a GM part number? or remember the price? how easy is it to install that monkey?

thanks!