91 ZR-1 Cutting Out Under Load

[GregCrowe]

Do LT5's have camshaft and/or crankshaft position sensors?

Also, where is the ignition module located?

[GregCrowe]

Originally Posted by tccrab

The ECM's show up on eBay fairly often.
There's one for sale right now but I'm *very* suspicious.
It's *way* too cheap and I'm pretty sure that the LT1 version is not the same as our LT5 version.

TomC

How funny, just saw it. The auction says it fits an LT1, LT5, 3.1L Regal, Grand Prix, Lumina and Cutless........... LOL ! Could that actually be accurate ?

Originally Posted by GregCrowe

Do LT5's have camshaft and/or crankshaft position sensors?

Also, where is the ignition module located?

Yes, camshaft is located on the driver side head in between ports 3 & 5.

Crankshaft is located on passenger side of block.

Ignition module is underneath the plenum.

Neither 3 of these components go bad on a common basis.

[GregCrowe]

Originally Posted by Jeffvette

Yes, camshaft is located on the driver side head in between ports 3 & 5.

Crankshaft is located on passenger side of block.

Ignition module is underneath the plenum.

Neither 3 of these components go bad on a common basis.

Thanks Jeff. If you've kept up with this thread, I'd sure appreciate some advice on what to try now. So far I have:

1. New Plugs and Wires
2. New Fuel Filter
3. Tested both fuel pumps...... tested OK
4. O2 sensor readings look ok
5. New Accel injectors and Fuel Pressure Regulator

ECM ? Coils ?

[gbrtng]

Originally Posted by GregCrowe

How funny, just saw it. The auction says it fits an LT1, LT5, 3.1L Regal, Grand Prix, Lumina and Cutless........... LOL ! Could that actually be accurate ?

The L98 ECM crosses to about 10 other GM applications. The LT5 ECM is specific to the ZR-1. Check with your local parts store or junk yard.

Originally Posted by GregCrowe

ECM ? Coils ?

Coils.


When hot, pull each plug wire and listen for the sound of the spark arcing.

[GregCrowe]

Originally Posted by Jeffvette

Coils.


When hot, pull each plug wire and listen for the sound of the spark arcing.

I don't think that will help. When hot, the car idles perfectly and runs perfectly unless under fairly heavy load.

[Pete]

I would try changing the spark plugs again.
It's cheap and easy.
Just try the cheap AC-Delco 41-602 cost about $15
You never know if some parts guy droped them.
I seen a guy throwing plugs on the counter from about 10ft away to see if he could land them on the counter like he was playing basketball
Otherwise check Coils.
Pete

[GregCrowe]

Originally Posted by Pete

I would try changing the spark plugs again.
It's cheap and easy.
Just try the cheap AC-Delco 41-602 cost about $15
You never know if some parts guy droped them.
I seen a guy throwing plugs on the counter from about 10ft away to see if he could land them on the counter like he was playing basketball
Otherwise check Coils.
Pete

The car runs the exact same as it did before and after the spark plug/wire change. I can't see any reason to change the plugs again, especially considering how the problem has it's weird intermintantcy, appearing after the car sits while being hot.

[LT5-Lee]

Originally Posted by GregCrowe

Haven't had a problem with this car in years until today. The car had been sitting for awhile so I decided it was time to break it out of the garage and take it for a spin. We made a 10 mile trip and the car was perfect, even while spanking a Mustang on the highway. After sitting for 30 minutes, we hopped back in and the car immediately had a problem.

At idle, it's perfect, at highway cruise, it's perfect. At any kind of load situation, it has a stuttering, cutting out problem. The heavier the load, the worse the problem is. If you put the car in 5th gear and bog it down at like 20 mph, the car literally shakes.

I'm almost positive it's not a mechanical engine problem. It seems electrical or sensor/vacuum related. The only problem I have ever had with this car is a little 5 cent clip falling off the arm of one of the secondary intake flap solonoids. When that happened, it was just down on power.

Any ideas? I'm dreading having to take this car into the Chevy dealership with a blank check.

Edit: Forgot to add, it makes no difference whether the secondary systems are engaged with the key. Either way, it has the stuttering problem.

Howdy, I was just curious if anything else has been learned since the last postings?

I am very curious as I think I have basically a '91 with "carbon copy" symptoms of your problems also!

I just started checking everything before a plenum pull, but I already have RC injectors and a fuel filter replaced. I guess I was hoping it was bad gas, but I know better since it ran good without any fill up in between.

Anyway, just hoping it is not a ECM.

Lee