OK... its still going on. Bad stumbling almost shakes the car to death. Getting worse. I MEAN BAD!! I put in new plugs last weekend and put different coil on. Checked the TPS out(ok) but I think it may be acting up. Wondering if its my fuel pump or TPS or IAC or EGR or what? I cleaned my IAC up though and seemed ok. It doesn't do it all the time. Usually occurs after I drive it for awhile and then when the motor is in a light strain,(going uphill or shiftng 1-2 w/ a T5) it seems to act up really bad. Usually I let off and push the clutch in. This is really getting on my nerves. Could it be a MAP? I got that code33 but thought it was maybe because the motor idled down really low and then died. aka-Low vacuum sensed at MAP? Also wondered if it was my cap and rotor or wires like that IROC guy had on this board. How do I check them? Well, any help GREATLY appreciated. Thanks! :-)

P.S.-After it acts up like this, when I'm sitting still and rev it up it sounds like it has a cam or a miss in it thru the rev range. WIRES? Cap/rotor?

THANKS SO MUCH!

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

When you changed the plugs and the cap/rotor did you make sure you got the plug wires back on the cap in the correct order?

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

I only changed plugs. I got the wires on the right plugs too. I was thinking about putting a new cap/rotor on it this weekend. Maybe that will help!? Later

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

No one else??? Come on, any ideas appreciated!!!

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

I was experiencing bad shaking. I checked everything and found nothing. I took it to the dealer and they checked injectors. I had two gone bad. One was bad enough that it was causing low ohms, high voltage. The keep the high voltage from frying the ECM, the whole drivers side bank injectors were turning off. This made the car shake really bad. To check the injectors, the just took off the wire clip, and use an ohmeter to check ohms. One was 3.4, they are supposed to be about 16 or a little over. I was not recieving any error codes though.... you might consider checking the injectors. Could be the problem.

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1991 WS6 Trans Am
Dark Green Metallic
Camel interior
305 TPI
TH 700-R4, Auto
T-Tops, PW, PL, PM
Keyless entry, alarm
Flowmaster Muffler
Monza Dual Tips
K&N Filter

 

Hey-
Thanks, I'll check them. I had a set go out a year and a half ago or so. I measured resistance on them then, and they were shot. I'll check them out and see. I didn't check them yet becuz back in October '00 I had a bad misfiring/stumbling/idling problem and I figured injectors and checked them to make sure. They checked out ok and it was actually my DAM Accel 8.8 super coil wire. It was arcing!*$%# Well, I'll check them tomorrow. That makes sense what you say. It just dies like half the motor is shutting down temporarily. Thing is, it doens't do it all the time. And usually it will quit if you floor it or take the motor out of a bind. Although it is getting WORSE.


BTW- Where are you at in IL. I'm from St.Louis area except on IL side. I'm at college right now. NICE CAR TOO! It sounds like mine except mine is a GTA and a 5-speed. Got any pics? Later Same color though... check it out.

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Sounds like a vacuum leak. Take carb cleaner and spray it around places that might be suspect and see if the idle goes up. If it does you found the leak. If you cant find any leaks than its something electrical. connect a dvm to map signal wire (light green) with key on engine off. Over 4.8 volts check signal wire for short. If no shorts map is bad. Under 4.6v than wires and map are ok.

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87z 383,afr 190's, crane hyd roller(224/230-.509/.528,112 sep),Ported and polished mini ram, 30lb inj, 3.42 gears, strange 12 bolt, tremec 5spd, , 1,3/4" slp headers.
"Just remember children, no man can beat you once youv'e found the cliterous." 'chef'

[This message has been edited by 87Z-ya (edited February 16, 2001).]

 

87Z-ya-
I was going to check for vacuum leaks this weekend. Maybe I'll find something wrong. If there is one, would that be causing the MAP to gay crazy and cause it to stumble and shake BAD? Also, I'll check the MAP for voltage like you said. I've never heard of that and was wondering how to check it. THANKS!

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

A vacuum leak could make it shake and stumble, it creates a lean condition.

 

Pull your cap and check for any corroded/excessively worn contacts and you may want to check the resistance of your plug wires but it's kind of a pain since you have to remove them.

To check the MAP, turn your ignition key to the "ON" (not start) position after you ground the diagnostic terminal (under the driver's side dash, use a paper clip or pick up a special key for it at autozone). Check the MAP sensor by separating the weatherpack connector and using three jumper wires. Take your voltage reading between the one in the center (signal wire) of the three wire connector and the leftmost wire (ground, the one closest to the vacuum hose connection). The third wire is a five-volt reference. Apply 10" Hg of vacuum to the sensor with a vacuum pump and the sensor voltage output should be around 1.2-1.3 volts. If the voltage change to 1.2 is slow, the sensor could be defective (it should respond to the vacuum almost instantly). Make sure that little vacuum hose to the sensor doesn't have a hole in it, I fixed one with electrical tape once upon a time.

Hope this helps you man, if the sensor checks out OK I'd suspect the EGR system.

 

One more thing, check your fuel pressure if you have access to a gauge, should be 40.5-47psi with the ignition "ON" and should drop 3-10psi after you start it. Also, it should take a damn long time to bleed down after you take out the key.

Come to think of it, I accidentally left my MAP disconnected after a job once and my symptoms were similar to yours. Get back to us and let us know what you find.

 

THANKS!!! I'll let you know. Later

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

I replaced my cap/rotor today. It runs better but is still doing that crap. I checked for vacuum leaks and didn't find any. What should I do now? I still need to check my injectors and fuel pump though. Later!

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

How old are your plugs wires? If the miss some at idle and when a load is put on the motor IT GETS WORSE( more throttle/or going up a hill) chances are it is a plug wire. Loosen all the wires on the cap. crank the car. with it running(better in gear/load, may need a friend),pull each wire and kill that that cylinder. If the motor dies down , then that cylinder is hitting and is OK. When you come across one that doesn't die down then that cylinder is the problem. Then check the spark at the plug wire/sparkplug end. If it has it then maybe you cracked a plug/ if it is not firing then it is the wire. We need to do this first before we go any farther. Also, Make sure the firing order is not messed up SBC firing order(18436572)
PS BECAREFUL WHENPULLING THE WIRE, IT WILL LIGHT YOUR *** UP IF IT SHOCKS YOU. WERE GLOVES AND US A PAIR OF PLIERS WITH RUBBER HANDLE/PLASTIC!!!!!

 

Might wanna pull the injector connectors instead since it's a little easier, but the man has the right idea. Did you ever check that MAP sensor yet?

 

Hey! That kind of sounds like what its doing. I thought maybe plug wires but was too lazy to change them. I figured I'd do it when I have my new 350 on the engine stand but I may do it sooner. I'll try that and see what it does. I was wanting the TAYLOR custom fit 8mm from Summit. Any good? Thanks again... I'll keep you all posted, althought I won't be changing them until next Saturday. Later guys

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Hey- I haven't checked the injectors yet, I ran out of time. I'll check them and I'll try and check the MAP also... next weekend that is. God I wish I was at home and not at college! No garage SUCKS!

BTW- I'll probably change wires anyways, since they are pretty old! Later

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Well, I put some Taylor 8mm's on yesterday. Runs a little better but is still acting up. Today it was horrible. Basically NO power. I had to rev it to about 3000rpm's and slip the clutch out to get any power to move the DAM thing. I checked codes and it threw a 22 and 33. It has shown 33 a few times but I figured it was becuz of the very low idle a few times and that it sensed low vacuum/high voltage at the MAP. Now, today I got a 22... TPS. Is this what it is finally? I ordered one for aobut $40 so I figured I'd give it a shot. What do you guys think? Let me know. THANKS so much!! L8R

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

I've had my gta for about a month now, and ithas a slight studder to the idle, the dealer said it was from the hyper chip that was in it. I later got a code 32 witch is the egr. when I checked the lines at the solinoid that controls the egr they were unpluged. I pluged the lines in and my car acted just like yours. The egr is stuck open allowing full exhaust flow back into the pistons. I simply unpluged the vacum lines and it runs fine ( cept for the slight miss at idle ). try unpluging your egr vacum lines at the solinoid on the pass. rear side
of the plenum.

 

Thanks, I may try that. Anyone else? I just wish I could fix this!

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

GTA91, I have a similiar problem with my 89 MAF car same code 33 (MAF signal high on MAF system). What do you have done to your car?
There is a table on MAF cars that estimates what airflow should be at a given RPM. I have a lot done to my motor so it takes in more air at that RPM thus setting the code. The computer thinks something is wrong with the sensor and the car goes into limp home.
Get a service manual and see what it says for the code. It will probably give a range of what the MAP sensor should read at 1500- 1800 RPM. Good luck

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355 10:1 , AFR 190 heads, LT4 HOT cam w/ 1.6 roller rockers, complete Superram intake, 58mm BBK TB, 24# injectors, screens out of MAF, MAT relocated, March underdrive pulleys, Streetdampner, Crane HI-6 ignition, 160 thermostat, K&Ns, TES headers(Jet hot coated), Mufflex 4' cat back, B&M shift Kit, 2500 converter, and 3.27s.

 

Try replacing the fuel filter if you already havent done so.

 

I already replace:
-wires
-plugs
-cap/rotor
-fuel filter
-cleaned air filter


Now what? Is it the TPS becuz of that code 22?? TIA

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

I had lots of codes and many weird problems on my '91 GTA a while back. My speedometer would drop to zero and the idle would drop down and the engine would stumble. Sometimes it would run fine. It got worse over time and I tried all the tuning checkup stuff. It turned out to be a bad ECM (computer).

The dealer wouldn't touch it because I have some speed parts, so replacing the ECM was my last resort. Luckily it solved the problem. It turned out that when I pulled the ECM, it had a sticker that said "rebuilt". That told me that it had already failed and been replaced previously.

I don't know if it would fix the problems you're having, but the confusing combination of codes would suggest it. How could all those different systems all go bad at once?

Hope this helps,
Dennis

 

Thanks! Heres what I thought. The entire time I was thinking it was a TPS problem. I've only had 2 codes... 33 & 22. 33 is MAP and I think it was set becuz of it idling down to like 300 or 400rpm's a few times. I figured that the MAP sensed low vacuum/high voltage like the code says. I didn't worry about it then. But now, the other day it was acting worse than it ever has... then out came 22. That is TPS. I figured thats what it has to be. Anyone else? Maybe I'm just in denial! haha Later

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Only way to know if either the MAP or the TPS is bad for sure is to break out the voltmeter and some jumper wires. Mine has idled down low like that and even stalled several times but it never set a code 33, so you still need to check the MAP using the procedure above. Hope this helps.

 

Guys-
Well, I replaced the MAP and TPS and made no difference. I guess I can rule out the TPS, but why did it set code 22? Also, I guess I need to check the voltage at the MAP yet, but I haven't had time. I also need to check injectors and fuel pump, but this thing doesn't do it all the time so how is that going to help? If its an intermitent problem, some of these parts could check out ok but possibly be bad... right? I also removed those 2 vacuum lines for the EGR from that little gizmo next to the distributor (pass. side) and that made no difference! Could it still be the EGR or a shorted wire on the MAP? I'm lost.

-A guy above mentioned the computer may be going out... how do I figure that one out?

*I REALLY need to figure this thing out. I can't hardly drive my car sometimes.


**Today it di it very bad and I almost couldn't get it back home. I'd try starting out and it would fall on its face. Slip the clutch out at 3000 rpm's and it would still fall on its face.

Well, THANKS for all the help so far!! I just wish I could fix it

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Hi guys, I'm new to this. Recently puchased a '91 305 TPI Formula with only 34K (Carfax documented) miles. Sold my '87 T/A 2 years ago. Anyway, just checking out the boards to acquire some preventive maintenance knowledge for future reference when I saw GTA91's delima.

It seems to me that bad injectors are a very consistent problem (when they are bad) meaning from my previous experience, the motor does'nt run better some days than others, so I dont think it's injector related. So, basically I feel that if you are recieving 22s and 33s and replace the relevant components and you still get codes and no positive results - the ECM must be on its last leg. What do think? Just a thought.


I wish you luck man!

nFORM91

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Proud newly acquired '91 Formula 305 TPI a4, 34K miles, Factory Black on Black all stock - no current mods (might keep that way!). Rims are '91 T/A black Diamond Spoke 16x8s. 20% tint & Black Widow Alarm system. Very near future plans: K&N filter, catback Flows, fresh paint job, new 255ZRs all around.

 

WElCOME!! I'm starting to think the same thing. Tonight I set my TPS again and drove quite awhile. My SES light came on and off about 100 times and it had a high idle. Then while sitting idling in a lot... after awhile it would suddenly idle up to about 1800rpm's. I'm sure the TPS is fine, but I got code 22 again! Is my computer going out or what? I'm gonna replace the fuel pump this week either way. It has 144k on it and I'm sure its not helping. It sometimes wants to cut out at high rpm's also.

*Is this a bad combo of fuel pump and/or computer?

TIA! I appreciate all the great help so far!

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Hey GTA... I just thought of something! Perhaps your ECM is trying to compensate for a choked fuel line (or diminished fuel pressure) by raising the idle.

One thing I learned (and I'm not a tech) is that the computer will first try to correct the problem before it shuts things down. I think your car is starving for appropriate fuel flow or pressure. Man!... You've gone thru alot and replaced alot of key parts! You should be very close to solving this.

Oh! another thing, is your ignition system stock or mod? When you changed plugs did you check for unusual carbon patterns?
If ALL plugs showed equal carbon burn that's a good sign.

Also, have you replaced the fuel pressure regulator? Coil? Good luck!

nFORM91

 

Thanks! You think the fuel pump will fix it then? Fuel lines should be fine. I'm replacing the FPR with a Holley AFPR when I put the 350 in. I've already replaced fuel filter and new coil also. Ignition is stock so I figured it should be ok? My dad is a mechanic of 30 years and he thinks its fuel starvation too! Thats why I overnighted a fuel pump. I WANT IT FIXED! He thinks thats what it may be, but I check on here for newer-up-to-date computerized mechanic's input. He's old school and VERY smart, but ECM'd EFI's aren't his specialty. Although by time we get done w/ my car, they may be! haha I'll let you all know if the pump solves it. I may swap a O2 in also. If this doesn't fix it, I may go to a used ECM and AFPR????

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Hey GTA... I think your getting really close to solving this thing. Did you notice any significant improvement at all after replacing anything? That might be the clue you need to hone in on the problem.

I tell ya... when you DO finally solve this, it will be a grand educational experience for all of us! Hey, have you replaced your fuel pressure regulator yet? You know, with the exception of a new wiring harness and ECM, you've replaced almost every sensor imaginable that could be responsible for the problems you've experience so far.

To me, that only means one thing... You're getting damn close to solving this! Good luck with the fuel pump man! Keep us posted.

nFORM91

 

Thanks man. I noticed a HUGE difference with the plugs/wires/cap/rotor! It hauls *** now when it runs right and gets fuel (hope thats the problem). I'll let you know how it goes tomorrow night. Can't wait to get this thing fixed! I've got a T56 bought and some 4.10's on the way... now if I could only get my L98 done!!! Later

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

GTA... A new 350, 5speed and some gears too? Sounds nice. My future aspirations include keeping my '91 FORM OEM (only 34K miles ) and one day (not too long from now) acquiring a rare '91-'92 SLP Firehawk w/factory 'Vette ZF 6 speed. That out the box is mod enough for me. Aftermarket scares the s#!t outta me - too many headaches in the past. SLP seems too have come up with a great combination of performance mods that work together with F-Bodies.

I know... enough with the plug for SLP Engineering Are you planning on installing you new drivetrain in your current car or another car? Just curious?

nFORM91

 

Check out my website to see it. I'm gonna put the ZZ4/L98 combo with a T56 and 4.10's and a SLP rearend carrier. Hope it all comes together good. Talk to you later.

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

If I were you, I would do a fuel flow test and fuel pressure test. That ought to tell you if you are experiencing fuel starvation. ~Arnold

 

GTA...

The mod list you're preparing looks pretty cool... should go down the road real nice when you're done. You said your car "hauls *** now" earlier after you changed plugs, wires, cap and rotor? Did that finally do the trick?? Any more codes??

nFORM91

 

I put in the new Holley pump today (255lph), it made no difference in my performance. Its still shaking and stumbling horribly. I tried taking it down the interstate and almost didn't make it back. I guess I'll do the 02 sensor next. How do I know if my FPR is bad? I guess those 2 and the the ECM? Later

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'91 GTA:
www.fbody.com/members/91WS6GTA

 

Bringing this back from the dead. But did you ever get this problem fixed, and if so what was the problem? I'm having a similar problem.

Thanks

Robert

 

Had sim. problem. roberts with 87 camaro, coud be MAF sencor (code 33 on older than 1989) wont hold on the 91 i guess And dont count on the readings on MAF 0,5 - 4,7 volts...MAF have a frecvency reading too, only to trace with a scoope ........

 

It was just the TPS connector on my car that caused all those problems way back then. It wouldn't make contact sometimes causing sever stumbling and stuff but when you'd floor it to WOT it would run fine b/c the ECM wasn't looking for a TPS signal anymore... at least that was my guess. Anyways, I cut a connector off another GM car at the junk yard and spliced it in and I've never had a problem again. That's all it was!