billwineberg

L98 TPI MISFIRES, now will NOT Start! - - > PLEASE HELP! Need to use this car!

Car is 89 Corvette L98, the car was fine, then started, sputtered and stalled then would not restart, checked and no spark, had it towed home.
Removed distributor cap to note the ignition rotor had come loose,
So I replaced cap and rotor,
Car ran but misfired, and then would be hard to start or no start,
I then replaced ignition coil, no better.
I then replaced ignition module, no better.
Checked the pick up coil with ohmmeter as per GM manual and tested OK.
Car then would start but misfire and run crummy,
Just for the heck of it, I Swapped MAF sensor with one from my Van TPI and car ran fine,
Then put old MAF back in, car ran fine, for a day and a half.
Then misfire was back, it is mostly when stepping on gas, it feels like it hesitates or bogs and does not want to accelerate.
Ran for 50 miles that way, then started up and moved to garage,
Tried Unplugging O2 sensor, still the same.
Tested ignition wires and condition of #1 spark plug, all OK,
Ran car removing one plug wire at a time to see it was just a one cylinder problem.
Then car would not restart,
Cranks over just fine.
Has spark, although it could be weak or slow, hard to tell it was so damn hot and bright out.
Car seems to have fuel psi at the Schrader valve as it is under psi.
Jumped Fuel Pump Relay and car started and ran fine, then later it did not.

So I think the problem is ignition and it is definitely intermittent and getting worse,
It has not been able to restart for hours now.


Question: Will a malfunctioning VATS let the engine crank?

Question: Could a bad pick-up coil cause this problem?

Question: Would a bad TPS cause a NO start?

Please help!

Thanks!

-=Jeff=-

If it was VATs, it would crank with no fuel. VATS shuts off the FUel Pump.

BAD TPS should not be an issue for starting I don't think

I also don't think it is the pick up coil since you said you tested it.

Did you swap back to your VAN MAF again?

I am thinking it could be the ECM, are there any codes?

flyersfan1088

If it was VATS, it would not crank. It would do absolutely nothing. At least that's what it did on my car.

jfb

Use your timing light and see if the timing changes between running ok and not running ok. An ohmeter test of the pickup coil is not conclusive. The timing light test might tell you if you have a worn loose timing chain.
Malfunctioning VATS will not allow the starter to crank.
A bad pickup coil could cause your problem.
Bad TPS will not cause a no start.

Measure the resistance of each plug wire, they should be 5000 ohms per foot and wiggle each end to see if the resistance is stable. At night with the engine idling, look for sparks along each plug wire and install a new loom or new wires and dress the plug wires to not touch engine parts.

billwineberg

thank you for your reply.

NO Codes

I jumped the Fuel Pump Relay and heard fuel circulating and the pump run, but still no start, so that should eliminate the VATS, right?

I will try to get a psi gauge tomorrow to test psi but i smell fuel from the exhaust so i think it's getting fuel, at least enough to where it should start.

Yes swapped MAFs back and forth, still no start.
I think it should start and run without the MAF anyway, right?

any tips on where to get an ECM?

billwineberg

thanks guys,

IF I could get it to start now i would test with a timing light.

timing chan set should be fine, have a new double roller in there with less than 10k miles on it.

anyone know of a good aftermarket replacement distributor?

SunCr

I don't see where you checked the MAF relay which is powered up through either the oil pressure switch or ECM via the fuel pump relay signal. Jumper the fuel pump relay with 12 volts to Pin G at the diagnostic link and with the MAF disconnected, check for 12 volts on the power or purple wire.

pablocruise

Additionally, you can visually see the elemnt in the MAF glow during it's burn-off phase after you turn the key off.
You have basically rebuilt the distributor, so might as well get the p/u coil. Mine was $15.00 from the local Chev dealer.
If you need to borrow a known to be good dist, burn-off relay, VATS module, and or ECM off an 89, you are welcome to borrow mine. I'm not using them because there is no motor in my 89 :cry


[Modified by 89 Paul in Cal, 10:25 PM 5/2/2004]

88vettelover

I had a very similar problem in my 88. And I did the exact same things you did.

Replaced plugs, wires, cap, rotor, module, coil pack, checked it all out.

Turned out to be fuel pump. I borrowed a buddy's gauges and checked and sure enough it was the pump.


:confused:

mitymek

yea definately check the fuel pressure.pressure can be low and it wont fire but still appear to have plenty at the schrader valve on a visual check.
that bit me once on a van i was troubleshooting.

billwineberg

thanks guys, i have a lot to check today, hope i can find the time.

Paul thanks for your generous offer, i may take you up on the ECM to try, if all else checks ouy ok.

IBEAM700

When my ECM went south it didn't throw any codes either. Purchased the replacement from Napa for about 110.00 with a 12 month warranty.
The Napa ECM went bad two weeks later. Napa replaced it under warranty, and its been fine for the last 2 years.

I also purchased a spare ECM off eBay for about 35.00 just to keep in the Vette as a spare.


:cheers:

billwineberg

plugged the maf relay connector in to another relay (the MAF relay is the same as the cooling fans), no change.

SunCr

You need to make sure it's getting powered up - relay could be fine.

billwineberg

would that matter? as my van has 5.0TPI from a 87 GTA once ran and would start without the maf plugged in, so wouldn't my car at least start in warm temps?

forgot to mention the car did start this morning i think because cooler weather this morning, would not start to save it's life even at 8pm last night as it was still hot, 88 degrees out! At least i have it in the garage now! where it is in the SHADE!!!

the problem started on hotter day 100+ and then it was another hot one when it came back, this morning was cooler 70, but temp is getting up there...

SunCr

It's plenty hot here too! Generally, if the relay isn't powered up, the fuel pump isn't running. Fuel pump should run with ignition on or once the oil pressure switch sees 4psi. That might explain why it starts cold - thicker oil. Another thought would be the coolant temp sensor is out of whack. At 100 degrees, it should be 1800 ohms across the terminals; at 210, 185 ohms. You might want to obtain a scanner, it will show you lots of good stuff.

billwineberg

It keeps getting hotter here, LOL

I had jumped the fuel pump relay and heard fuel circurlating, so it should have fuel, question is if there is enough PSI.
No parts stores here stock a psi gauge at any store around here (rolleyes) have one on order for tommorow...

I have a Snap-On MT2500 Scanner and the ECT reads OK. Even if it was bad I would think the car would start most of the time, yes or no?

Where is the ECT (coolant temp sensor) located?

I picked up a pick-up coil, but hate to r&r the distributor if that ain't the prob, and yup damn it's hot outside!

kabnvtt

I will tell you I had the exact conditions on my 87 and it was the fuel pump, the only way I found it was with a fuel pressure guage hooked up while driving around. It started to run like mentioned,after the pump ran for a while, and as soon as it started running bad the fuel pressure was all over the place. Slapped in a new pump and it ran perfect. Good luck

SunCr

102 here and I'm 10 miles from the Coast! The coolant temp sensor is on the front of the manifold under the throttle body - yellow and brown leads if I remember correctly; however, if you scanner reads ambient on a cold motor, that ain't it.

billwineberg

car has been starting since it's inside and not getting hot...

i unplugged the maf and car still ran, just crappier.

it does backfire out the intake or exhaust on occasion since it is running crappy,
could it still be the fuel pump?
making it too lean?
but sometime running it smells rich, othertimes not really, or i'm getting used to it, LOL.

i ran about 2 minutes and no glow from MAF Sensor, even after shut off.

i jumped the 2 thick wires of the MAF Relay and still did not see any glow.

how should i test the wiring to the MAF Relay?

car i run direct 12v to what terminal on the MAF Relay connector to get the thing to burn-off?

Fuel PSI gauge from PepBoys $40 was wrong type, it was for TBI, so not good on TPI, another on order from NAPA $53 will be in tomorrow already paid for,
if not right I will go to a special hose place and get all the pieces and make my own for less $.