I know the title of this maybe confusing, let me tell you whats happening and hopefully someone can help me. The other day as i was driving my car and i would accelerate from moderatly to aggressivly my car would kinda slug back and forth as i was accelerating, basically like how some new cars if you have them in park you can not rev the engine past 3K. I knew my timing was probably off so I got out my timing light, its an adjustable kind and re-set my base timing to 7 degrees. (un-hooking the tan wire and adjusting everything etc.) After I did this the car felt alot better and as I was driving my throttle response felt alot better too so I was like YEAH! Anyway, last night im driving home and my check engine light comes on but my car is still running fine and all my gauges looked good except for my gas gauge that doesnt work. I got it home and decided to disconnect and reconnect the tan wire thinking maybe it was not getting a good connection. I did that and I started the car and the light did not come back on so I wak like cool. Then this morning about 15 minutes into my drive the light comes back on and I notice the sluggish feeling kinda return as I am accelerating. I make it to work, turn off the engine, wait about 30 seconds, then turn it back on, light still on. I turn the engine off again, disconnect and reconnect the tan wire, start engine back up and light stays off but as I sit in my car and rev it to 2K I can feel the engine dropping down a few hundred RPM's and then coming back up. I rev'd it to 3K just for a few seconds and it gets worse. My check engine light has not come back on but I would not be surprised if it does on my way home. Should I consider buying a scanner? Did I not do my base timing correctly? If anyone has any ideas as to what might be causing this please let me know. I know this is not right and can not be good for my engine.

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Struggling College student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

 

under the drivers side dash you'll see an access port for where you would plug in a scan tool. Take a paper clip and jump the top to right plugs together then turn the ignition on. The SES light will flash a code 12 (or13) 3 times to tell you that you are in diagnostic mode and then it will flash a bunch of other codes. The other codes are the trouble codes that a scanner would tell you about. Once you get those codes come back and we'll help you out more...

EDIT: the reason that the car is running doggish is because when the light kicks on it gets thrown into limp mode...

Good luck,
Mike

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1989 RS.. Newly installed 350,bored out 30 over, Hypereutectic pistons, double roller cam, double roller timing chain, accel wires, blue streak cap and rotor, rapidfire plugs, chevy caprice 350 chip, 200* fan switch, 3 angle valve job.

[This message has been edited by burntblues (edited May 02, 2001).]

 

Thanks for the quick response Mike.

I have been reading up on how to pull codes here on the message boards. It seems pretty easy. I will do it once I get home from work. It seems like other people have had similiar problems to mine. Looks like it might be a possible EGR valve or O2 sensor. I will update you on what I find out this evening. If it is the EGR valve, isnt it located under the plenum of the TPI? Is it a really big PITA to change?

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

 

yeah, on the tpi engines its under the plenum and you have to remove that first. I'm not sure how difficult it is to get to it on the tpi's though I've never had to work on one, I've only done the TBI ones. A good way to check is to try to reach in and push evenly on the diaphragm of the egr with the engine running at idle. if it moves fairly easily the EGR is probably still good.It should cause the engine to stutter. check all of the vacuum lines around the egr and check the solenoid that controls it. If everything seems to be good you may need to remove the EGR and clean out some of the carbon or replace the unit. An egr is expensive, so you might want to check out the junkyards...

Mike

[This message has been edited by burntblues (edited May 02, 2001).]

 

I am going to hope and pray its not the EGR. I will pull the codes this evening when I get home from work and update on what I find out. Thank you for all of your help Mike.

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

 

Just another idea. I had the EXACT same problem that you did after I was fiddling with my timing one day. Car wouldn't pull up to speed very well, jerked into gear, wouldn't rev. The SES light would also go off sometimes after the car was turned off and the restarted. The ECM won't take back over the timing once the bypass (tan/black) wire has been separated until the car is shut off and restarted. I knew it had to be something with the Electronic Spark Timing since I got a code 45. I am guessing (stress guessing) that this is what you will see. It ends up that I had a bad connection along the ground wire for the EST at the distributor. Sometimes it would make a connection and sometimes it wouldn't. Check all the wires off the distributor for breaks. I think you should be seeing approx. 4.5V on the White wire with the car running. Don't quote me on this. I don't have my manual handy right now. Good luck.
bsa

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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 23# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter

 

Hi Mike and irocbsa,

I drove home this evening and sure enough the light came on before I even got on the highway and my acceleration has gotten worst. It "chugs" really hard when you are accelerating. Anyway, I did the wire trick to pull my codes and got a code 33 and 42. I ran the test twice to make sure I read it right. According to the info in the tech area 33 is High voltage (low vacuum) at mass air flow sensor or (MAP sensor) and 42 is Fault at elect. spark timing circuit OR Fault at direct ignition system OR Fault at fuel cutoff relay circuit.

I did replace my fuel pump relay about a month ago because my car has been having a hard time starting and it was suggested that might be it. So right now I am kinda wondering where to start. I know MAP sensors seem to be expensive new or kinda cheap used but I have heard it can by bypassed as well, is this true? As far as the the code 42, I dont know where to start. Any ideas?

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

 

If anyone has any ideas please let me know. My IROC is my daily driver and I need to get this fixed ASAP. All info will be greatly appreciated.

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

#3 Gone but shall never be forgotten. Long live the legacy of the man in black. RIP Dale Earnhardt "The Intimidator"

 

I took of from work early today because my allerigies where killing me. My car drove ok tow ork but the SES light was on the whole time. I got it in to go home and it started up, struggling to keep running but the SES light had not come on. I sat in it for a few minutes letting it warm up, it was still struggling. I slowly put my foot the gas and rev'd it up to about 2,100 RPMs and the right then the SES light came on and the engine smoothed out. The whole drive home (40 mins) with AC going was nice and smooth but the SES light was on the whole time. I pulled into a store to get some more allergy medicine, maybe in there for 10mins, came back to my car and it would not idle worth crap. It kept loping like it had some huge cam in it. It died twice. I was able to limp it home and park it and I could hear it kind back firing through the intake under the hood, but the SES light never came on. What is wrong with it????? This is really starting to scare me. I need my car because the buses here do not take me to work and the cab is $50 each way. Please, if anyone knows anything about this please tell me. My email is chevyguy1969@hotmail.com and my cell phone is 512-297-8842 if you want to call me, Im getting desperate.

Thank you,
Jeff

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

#3 Gone but shall never be forgotten. Long live the legacy of the man in black. RIP Dale Earnhardt "The Intimidator"

 

Sounds like irocbsa nailed it. If you're getting a electronic spark timing fault, it sounds like you've got a bad connection or a short going on. The car's struggling because the timing is bouncing all over the place.

 

The latest,

I have been reading on here and I am not alone with my problem. I have reset my base timing to 6 degrees and disconnected the neg. battery cable to let the computer reset. Connected it back, started it, and care still runs crappy. I checked to see if the codes where still there and they where not, I guess disconnecting the batter is what did it. From what I have read on the different posts around here, people have replaced all the relays for the MAP, the MAP itself, O2 sensor, and checked the voltage on the TPS. After my car cools off some I am going to check te voltage of the TPS and I guess I will drive up to the suto parts store and start swapping out new relays. I did notice when my car would run it smells like it is running really rich, you can smell gas in the exhaust. If anyone else has any ideas I am completely open to them. Thank you for all of your help.

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

#3 Gone but shall never be forgotten. Long live the legacy of the man in black. RIP Dale Earnhardt "The Intimidator"

 

The mystery goes on....

I swapped out both of my MAF relays on the firewall and reset the ECM. Still no luck. Car runs like crap till the SES light comes on, once it does it runs fine, just doesnt get up and go 100%. I did find my code 42 problem,one side of my dist. cap was loose, I tightened it and the 42 has not returned but I am still getting code 33 and I am getting the 3 12's before I get the 33. Autozone sells a new MAF for alsmot $150.00. I am going to research and see what I can find on ehre about bypassing it. I was never able to test my TPS. How do you test it? I read on here you take a volt meter and measure the voltage coming across the top 2 pins on the TPS but I dont know where you hook the leads to. You have to have the TPS hooked up to test it. If anyone knows how please explain in detail. I will keep updating this as I find out more.

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

#3 Gone but shall never be forgotten. Long live the legacy of the man in black. RIP Dale Earnhardt "The Intimidator"

 

The conclusion, I hope

I researched the board some more and found out a simple way to test and see if my MAF is bad. My car was running really bad with the MAF hooked up so I disconnected it while the car was running and WOW, the SES light comes on and the engine smoothes out. Looks like I am going to try and get my hands on a used MAF. I am going to post another msg. to see which ones people buy. New, reman., or used.
Thank you to everyone that helped me.

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Poor college student(donations welcome ;0) with an all stock 1988 5.7L IROC-Z Hardtop, Auto. trans, white ext. w/gold accents (soon to be silver), black custom cloth interior, 4-wheel discs and G92 pkg. Car is dead stock. Has only standard Z28 power options and all the IROC performance stuff you could get. No pwr. seats, mirrors, or rear defrost.

Best run: 1/4 14.90 @ 92.7 MPH

See My Car here: http://zap.to/chevyguy1969

#3 Gone but shall never be forgotten. Long live the legacy of the man in black. RIP Dale Earnhardt "The Intimidator"

 

Glad you found the answer. If you need any further help I can send you a trouble shooting flowchart for the MAF. Good luck.
bsa