I got a 90 RS 305 TBI. It was giving code 43 for a while, but I put in a new ignition module and that eliminated the code, but the car still runs the same. Here's what it does: When I start it up in the morning, I have to immediately bring the rpms to about 3000 (I know that's bad) and hold for about a minute or so and then slowly let off the accelerator or else it will die. It dies under load, sometimes it idles fine, other times it idles eratic, the car sometimes wants to surge, and always hesitates upon initial driveaway from a stop. When its warm, its very hard to start. I have to pump the accelerator to keep it alive while in park but it fights it and usually dies. More recently, the starter has begun to not engage at all sometimes, crank and crank but not fire the motor sometimes, and crank the motor over fine other times. The SES light always comes on when it dies but no codes are set. I've had it in 7 times to find out but everyone seems to guess and contradict everyone else. Here's what shops have told me:
Bad EGR (one shop said it was bad another said it was fine)
Bad fuel pump (8 psi at one shop, 9 psi more recently)
Bad starter motor (new starter less than 2 yrs ago)
Bad fusible alternator link (fixed it-no difference)
Bad IAC (no luck)
Bad Ignition module (no luck)
Bad MAP (no luck)
Bad coil (no luck)
Dead battery (replaced it two hours before taking it in and they still insisted it was shot)

Now I think you can see where this is going. The car really is not driveable and it has pretty much ruined my view on the third gen platform as well as GMs build quality. If anyone KNOWS FOR SURE what this is or has any ideas, please tell me because I really am fed up with this-I can't go anywhere and now summer is in full swing while the car sits in the garage.

 

the first thing that comes to mind when say erratic idle is EGR. my car was similar in the idle department. slapped on a new egr and now she purrs. it was only 35 bux and easy to install on our lo3's. if it doesnt help, take it back and get a refund.btw my car used to stall at idle sometimes and the ses light automaticly comes on, its not a code. it is the same thing when you turn ur key to the 1st position. it comes on and then goes off when you start it. sorry i am not much help.

 

A possible quick test could be once you get it idleing ok, go pinch the EGR vac line, if it then dies/has trouble idleing, It can be a good indication the EGR is functioning properly Not really decisive, but could be a help....
As for fuel pressure, 8-9psi?! for PFI? (port fuel injection) I may be wrong about TBI, but even for the L4 the Helm says no less than 40.5 psi and no more than 47 psi. I can't find any mention of TBI specific on the 87 book, only "PFI and Carberated" So my guess is the shops thought you hadf a carbed motor since they run those lower fuel pressures!

Have you checked for vacume leaks? Pop the hood and listen for hissing.

Run a fuel pressure check and make sure the injectors/regulator is holding pressure.

Replace the fuel filter.

None of these should be overly expensive, the fuel pressure gauge will be most expensive since the TBI's I have been told do not have the schrader valve...you have to get the $69.99 guage not the $39.99 gauge...or find someone to borrow a guage from The thirdgen F-Body really is a decent performance platform. You can really build up the suspension > 1.0 Lateral G, and the motors can really be brought up...like 10's on the 1/4 street/emmissions legal. They really are great cars They just need some TLC especially if you weren't the original owner of it...you never know how others treated it!

Anyone else?


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Corry Lazarowitz
clazarow@voicenet.com
clazarowitz@hotmail.com
1987 Pontiac Trans AM (GTA?) 350 or is it a 305?! TPI
SLP 1 3/4" headers, 3" cat back (stock cat
MSD ignition.
MSD Blaster SS coil.
3.73 Rear end gears
Accell 8.8 Wires
Bosh +4 Spark Plugs (Don't know if they really help but hell!)
Holley AFPR
Race Built Automatic trans ('vette servo, shift kit, tightly packed clutches)--just needs titanium gears now!
Newly gutted cat (the car gutted it's own cat!)
Hypertech Chip (Just found out I had it! :eek
More soon when funds are avail...

 

GT Killa,

Too many gophers in the works.... Just kidding. It sounds like you have a lean condition and/or a serious vacuum leak. Make sure the fuel pump is providing adequate pressure and flow, and that the filter is clean.

Check the EGR as recommended;

Check/clean/replace the PCV valve - it's basically a "programmed" vacuum leak;

Check for any vacuum leaks, including the intake, TBI base, hoses, and the power brake booster;

Clean the IAC control and IAC air passages, then reset the minimum air position;

Set the base timing to stock specs;

Check the injectors for leakage. This is easy on a TBI - just energize the fuel pump and place a piece of paper under the injectors in each bore. Any leakage will be apparent.

Good luck - we know what you'll be doing tomorrow. The car is a fairly stable platform and can be exceptionally reliable - especially with the TBI. It sounds like you might have been unlucky enough to get one that may have been abused or neglected. Once you get it in proper condition, you may have a different opinion.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

I may be wrong here but I thought that the TBI motors only ran about the same fuel pressure as a carb..?? Could someone give confirmation on this??
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 24# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter

 

Scouring the book, edit in 15mins-1/2 hour prob.....
Hmm, the book only lists the TPI motors codes, and the 2.8 L4 motors codes. Under carbed has a 5.0L listed for motors. Were TBI's avail in 87? If so I would guess it goes under the port injection. If not, you'll have to talk to another TBI owner. If you have a TBI and have checked/set your pressure, it would be obvious as a high pressure fuel system would not run at 9 psi, and a carb type pressure gauge would be pinned to max value (and probably be squirting fuel out the fittings!) if it was on the wrong system. That's all I can give
Corry


[This message has been edited by Corry (edited June 15, 2001).]

 

TBI fuel pressure is around 12-15.

It could be a million things, somehow you are gonna have to try and narrow it down between vacuum leak, ignition, or fuel.

It sounds like a fuel issue to me. TBI injectors suck, they are very problem prone.

 

This is just a shot in the dark... but have you checked your fuses? I had an injector fuse blow on my TBI a few months back. It would run, but like ****. Hope you figure out what's wrong.

 

I tested the EGR-it seems fine.

The fuel filter has about 7000 miles on it but this car has done it since maybe 2000 miles after replacing the filter so that should be good.

Timing is at dead even 0*.

The IAC is new and functioning.

The injectors are not leaking.

The plugs are pure white-very lean.

Fuel pressure specs are 9-13 psi for TBI and one shop said 8 psi and the most recent reading was 9 psi, so hmmmm...i thought a fuel pump either worked or it didnt-no "dying"-i thought it just plain quit working. I almost think its a cracked block. i do hear a hiss thats more apparent at startup and one shop said i had a TINY vacuum leak from the intake but not large enough to cause the car to run this bad. I know these are good cars but crap mine hasn't run right in over a year. I just don't know.

 

yes i also checked the fuses a couple weeks ago and they checked out fine.

btw-i bought this car from the original owner woman and she nor I beat on it at all. I also have all the maintenance records and all the paperwork so i know its been cared for.

 

How bout the PCV? I hadn't thought of that one, I have to go check mine since mine is also running lean, not too awfully bad yet, only enough to set codes at idle...and hesitate. I completly forgot about the PCV...
Next guess would be is that a MAF car? If the EXM is getting incorrect MAF readings it could lean out the mix thinking it was doing you a favor If it's not MAF, I guess it uses the MAP? or is it speed density? Whichever it uses I'd check, incorrect sensor readings, small vac leaks here and there, could be enough to squeak by the ECM and cause it not to set any codes. Does TBI have a throttle position sensor? That is a major factor in fuel metering from the ECM.
Does TBI have multiple injectors? If so are they all getting a signal to fire?

Just gotta track the problem down to the source

EDIT: Sorry, if it only uses MAP to determine incoming air, I saw you already tried that I always double and trible check my posts to make sure I'm not making an @$$ of myself Just want to make sure you know I did read your entire post, and the entire thread of what ppl are writing

[This message has been edited by Corry (edited June 15, 2001).]

 

already tested a new MAP sensor and that wasn't the cause either. The PCV valve was replaced about 7-8000 miles ago so i dont think thats it either.

 

does anyone else have any ideas? seems like everything thats been suggested I have already done or checks out fine. Whats missing?

 

Killa,

I hate to beat a dead horse, but you mentioned a "small" vacuum leak on the intake. That's all it takes. Repair that and go from there. You can temporarily seal the leak with Play-Doh (yup, the kid's stuff in multiple colors) to finish the diagnosis.

What kind of replacement PCV valve did you install? I had a TBI V-6 that was a real ***** to troubleshoot. High idle, lean, error codes, no low end power. It turns out the brand new Fram PCV valve was either incorrectly packaged or calibrated wrong for the engine. A new AC/Delco PCV valve solved the problem. By saving a buck on a replacement part, I had several hours of troubleshooting and days of frustration driving it.

And I didn't see any response to the brake booster test. Did you check it? All you have to do is remove and plug the vacuum line to eliminate that possibility. Remeber that you'll have no power assist for the brakes with no vacuum, so brake pedal effort will be higher.

You can do the same for the PCV valve temporarily, and the other vacuum lines. Jus tmark the lines and fittings when you remove them.

A leaking power brake booster will create a muffled hiss when the engine is running, and you may be able to hear that inside the passenger compartment. They can also leak a lot of air, effectively killing your idle.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

i tried the power brake booster and that checks out fine. i popped in a new PCV valve-no difference. i took it in for the 8th time today (5th time at this shop) and they had it from 7:30 to 5:30 and found absolutely nothing. they were real nice as always and didnt charge me a dime. i guess that ill just accept that this is how the car is going to run and just live with it and forget about it.

 

For what its worth, when I swapped my intake manifold I noticed a huge amount of gunk in the EGR passages at both the heads and the intake. I managed to scoop most of the stuff out and then squirted some carb cleaner in there. When I put everything back together I noticed the engine ran better.

Have you checked out your exhaust side yet? (O2 sensor, plugged cat). This may not be the direct cause of your problem but should not be overlooked. Hope this helps


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92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps, MacEwen white-face guages
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi

 

yeah the cat is new as of last year (of course it was toast two weeks before minnesotas last emissions test so i had to get one-go figure) and the O2 sensor should be fine. my mom is being VERY irrational and it really pisses me off bigtime. she wont let me drive my car, its been determined by me that after seeing the shop 8 times, it is not fixable unless i yank the motor and put in a new one and see if i got a cracked head/block, but i cant afford to finish my motor till its time to put it away for the winter, and i couldnt even sell it as is if i wanted to. yet i still pay the insurance for it to sit in the garage. i have no options and im just FLAT OUT FED UP BECAUSE I CANNOT DRIVE ANYWHERE. god i am mad.