I have a 97 z28 camaro 134,000 miles and nothing done to it other than a Moroso CAI. I have had the car about 2-3 months and at first it had a small bog when i put it in the floor. It got worse and worse as time went on and now its almost undriveable. Symptoms i am having are: Rough idle mainly after warm, stalling when sitting still, Loss of power, bogging when accelerating harder than just easing off. I thought initially it was for sure the OPTI but i went to advance auto parts saturday and got them to hook the scanner up. EGR and MAF codes were thrown along with P1870 i believe which was harsh shift 1-2nd. So i went by Auto zone as well just to see what there scanner said. It threw all 3 codes listed above as well as something like the fuel purge valve solenoid or something like that. Now correct me if im wrong because i am no mechanic by no means but i believe the MAF as well as the fuel purge valve solenoid could cause these same symptoms...? Thing is there wasnt once a misfire code. Could this still be the opti or has anyone had the same troubles as me and it have been this fuel purge valve solenoid or MAF? I have already tried cleaning the MAF with MAF sensor cleaner. Any feedback would be great! Thanks

 

Which specific numerical code for the MAF and the EGR? There are multiple for each, and each one can point to a different problem. P1870 is "Transmission Component Slipping". Might want to get the codes read again - write them down this time. Could the other mysterious code be for the EVAP purge solenoid, that purges the fuel vapor from the carbon canister in the driver side rear fender? Again, more than one code.... one for the electrical circuit that controls the purge solenoid, and others for vacuum in system when the solenoid is supposed to be closed and for no vacuum in the system when the solenoid is supposed to be open.

The problem you are experiencing could be from the MAF. If the MAF is faulty, there are two codes, loss of power to the MAF sets another code, and another code for irrational flow readings compared to the mass flow calculation using the speed-density method. Irrational flow could be due to a tear in the rubber elbow between the MAF and the throttle body, or the bottom of the elbow not being over the throttle body flange.

The EXACT numerical codes are required.

 

I have all of the codes printed out at home and will give a breakdown tonight after i get off work. Thanks!

 

Another problem could be a dirty MAF. Is it possible the K&N filter in the Moroso CAI has been over-oiled, causing the sensing elements in the MAF sensor to get coated with oil?

 

Well i actually cleaned the air filter and oiled it then cleaned the MAF sensor after that. But it ran like crap before i did that and it ran like crap after i did that.

 

I lost power on my firebird years ago and thanks to this forum they said check the coil wire for loss of power when accelerating.I did installed a new coil wire and that fixed the problem for me.Hope this helps.Later it happened again when my msd wire was just too loose and kept slipping off till I tightened the boot with pliers.

 

Okay the codes are as follows:

Code P1870: Transmission component slipping.

Code P0443: (Evaporative emission system) Purge/vent solenoid circuit condition. Probable cause; Purge or vent solenoids defective, check connector and wire, fuel saturated vapor canister, failed EVAP vent solenoid.

Code P0100: (Man. absolute pressure)/ BARO or MAF/ VAF(vane air flow) sensor condition. Probable cause; Vacuum hose off, cracked, or passage blocked- engine mechanical timing condition, Throttle body intake tube loose, off, or cracked, BARO/MAP (manifold absolute pressure) defective, VAF (vane air flow) MAF sensor dirty or defective.

Code P0441: (Evaporative emission system) small leak/no flow condition. Probable cause; Defective or loose fuel cap, EVAP canister or hose cracked- not connected, purge or vent solenoid defective, vacuum leak at engine.

Code P0400: EGR system fault (exhaust gas recirculation). Probable cause; Blocked passage on EGR system, failed EGR valve, EGR solenoid faulty, failed EGR pressure sensor where applicable, failed EGR position sensor where applicable.

This being said what could be causing my car to run like I mentioned above in the initial post? Any feedback would be great! I am not rich and do not want to drop a bunch of money on the car if I dont have to. Let me know what parts are cheapest/easiest to start with on this list that would play a part in the car running like mentioned above.

Thanks,

Dusty

 

Couple of suggestions - avoid generic code lists if at all possible. Shoebox has a list specific to the 96/97 LT1 OBD-2 codes (see OBD-2 tab at bottom of page):

http://shbox.com/1/Dtcs.htm

Even better, download a free copy of the 1996 factory service manual (virtually identical to 1997). Volume 2 of 2, Part 1 of 2, pages 6E-445 through 6E-942 have the complete engine controls for the LT1, including wiring diagrams, detailed trouble code descriptions with logic trees to track down problems, etc.

LINK: 4TH GEN SERVICE MANUALS - (1993 - 2002) - Firebird Nation


P0100 = MAF Sensor Circuit, Insufficient Activity

Common cause of this problem, moreso on 96's than 97's, is a break in the pink wrie to the MAF sensor, somewhere in the harness. Pull the harness connector off the MAF sensor. Check for damaged pins. Key on, check for 12V on the pink wire. Check for a good ground on the black/white wire. Plug it back in, and if your multi-meter has a "frequency" scale, start engine, let it idle, and measure the frequency on the yellow signal wire. Should be around 2,500 Hz. Exact number is not important. Rev the engine - does frequency increase with throttle movement?


P0400 = EGR System

The PCM cycles the EGR valve to admit exhaust gas into the intake manifold. The PCM looks at the MAP sensor to see if intake manifold pressure changes a specified amount when the exhaust gas is supposed to be flowing. If it doesn't see the MAP change enough it sets the code indicating no, or low flow.

This can be caused by an extremely low back-pressure exhaust system, or a leaking exhaust system.

Can be caused if the vacuum from the intake manifold, to the EGR vacuum solenoid, to the EGR valve is missing. Check for vacuum leaks.

Can be caused if the EGR valve is stuck open or partly open. This can also cause a very rough idle and rough engine at low RPM.

Can be caused by a faulty EGR valve, carbon on the EGR valve pintle, plugged EGR passage in the manifold.


P0441 = EVAP System No Flow During Purge

There's a vacuum switch on the passenger valve cover, to detect vacuum in the line from the carbon canister to the EVAP purge vacuum solenoid. Could be a faulty vacuum line, lines on the solenoid reversed (Shoebox has a photo of the correct piping), purge solenoid plugged with carbon particles, purge solenoid not working (see P0443).


P0443 = EVAP Purge Solenoid Control Circuit

Means the solenoid isn't receiving constant switched 12V on the brown wire or the solenoid is not getting a good ground from the PCM on the dark green/white wire to open the solenoid, or the solenoid is burned out. With the harness off the solenoid, measure the resistance across the two pins on the solenoid. Should be in the range of 15-30 ohms, if I recall correctly.


You know what P1870 means, and I know nothing about automatic trannies. You should read the factory manual on this one (Volume 2 of 2, Part 2 of 2, pages 7A-181)

The checks suggested above are a simplified list, based on what we see here most often. But there are several more possible causes for each code. To me, either an MAF that has failed and caused the PCM to default to speed-density mode, or a stuck open EGR valve could be your most likely problems.

 

Well then I will just start with the easiest thing first. I bought a new MAF and am going to put it on this afternoon and see if that fixes the problem. If not its onto the EGR... When i got to looking under the hood if I'm not mistaking there was not an EGR valve even on the car...? I will have to look again when i get under the hood been about a week since I really got under the hood and observed. Didnt have any idea at the time when i was looking for the EGR that it would make my car run like this though. I will update after i get the new MAF on.

Thanks,

Dusty

 

If you don't have 12V on the pink wire, a new MAF won't fix anything.

Go to shbox.com . He has pictures of just about everything.... best LT1 reference on the Internet.

4th Gen LT1 F-Body Tech Aids

 

So i put the new MAF on last night and the car is still running rough and sputtering when harder accelerating. But it is backfiring so it shouldnt be spark or opti or anything like that right? I also put a volt meter to the MAF plug tip and had nothing on yellow or black and 11.1 on the pink wire. Any feedback would be great!

Thanks,

Dusty

 

Hard to understand what set P0100. Your wire measurements are not conclusive.

11.1V on the pink wire is low, but it's possible that's what your battery was at.

Measuring voltage on the black/white wire means nothing. There should be no voltage on it, but you would get no voltage reading if the wire was broken some where between the connector and the PCM. It's a ground, but the ground is supplied by the PCM, so it is not at the same potential as the chassis ground. Measure the voltage BETWEEN the pink wire and the black/white wire. Should be close to 12V. Measure the resistance from the black/white wire to a chassis ground. Should be 50 ohms or less, not 0 ohms, because the PCM circuitry for the ground is in between.

There should be no voltage on the yellow wire, but again, voltage would be 0 if the wire was broken or healthy. First verify the MAF sensor is producing a correct frequency reading on the yellow wire. Then you would have to use a real time scanner to see what the PCM is reading for grams/second mass air flow. Should be in the range of 6 - 10 Grams/sec at idle. When you open the throttle, indicated air flow should increase proportional to the throttle opening.

Opti can produce misfires. Do you know what brand Opti is on it? You can run into problems if the rotor screws come loose and allow the rotor to come loose. Eventually the screws would fall out and the rotor would stop spinning, and probably self-destruct. The cap can encounter carbon tracking just like a conventional distributor.

 

Fred, I apologize but most everything you explained for me to do is almost a different language. I change my own oil, filter, alternator, plugs, but when it comes to more technical stuff I'm not that savvy. I got one of my electricians at work to check the volts on the pink wire for me. If it is something of that sort i will have to take it to a shop or get a friend that knows what they're doing to check all of that. I dont know what brand of opti is on the car never had to dig that deep. Hopefully it is just an EGR valve or fuel purge valve solenoid. I will have to make it back to the parts store sometime soon to get them to scan it again and see if the MAF isn't throwing any codes anymore and move on to the next code/part from there. Sorry for any delayed responses work schedule is normally 630-6 some weekends also.

Thanks,

Dusty