: I think I'm missing a few ponies!



FrankT
04-11-06, 05:06 PM
Hello all,

I had to have my engine replaced in my '99 STS with a new GM N* engine. After driving it for 20k I do believe its broken in. Since then I have determined that my new engine part #12567313 / L37 lacks some power, in comparison to the original engine. In short the new engine runs smooth, doesn’t use any oil and gets good mileage 20+ combined. No codes, data looks good. The engine just doesn’t have the crisp rip-power that I had before, it’s like I lost about 50hp.

Do you think it’s possible for the engine have the LD8 cams? OR possibly different lower compression pistons?
I can live with it but it would be nice to have my torque and power back to what it was.
Build date on this engine is 12/2004 if it helps.

Thanks for any help or suggestions

All I want is to chrip my tires again.:burn:

I think I need a cold one! :alchi:
Frank

auroradude
04-11-06, 10:54 PM
Well dont feel to bad...its what i have to deal with every day. Cant even squeal tires for CRAP.

davesdeville
04-12-06, 02:48 AM
Did you make the determination using the ass-dyno or a real dyno?

FrankT
04-12-06, 06:06 AM
Did you make the determination using the ass-dyno or a real dyno?

My ass-dyno!

Maybe i'm just use to the power and it feels slighty slower.

Thanks
Frank

davesdeville
04-13-06, 03:09 AM
Well if you're concerned about it, try a real dyno, most dyno shops will do a 3 pulls for $55 or so deal (more or less depending on the shop & where you live, but that's the going rate here.)

djb25
09-19-06, 02:49 PM
Frank,

Did you ever figure out what the problem was with you car?

- Damion

FrankT
09-20-06, 07:07 PM
Frank,

Did you ever figure out what the problem was with you car?

- Damion

:mad: :mad: :mad: :mad: :mad: :mad:

I saw your post on disappointing performance and I am disappointed with my performance too.

I don’t need a dyno run to tell you that this new engine L37 does not perform like my old L37 I have an A to B direct comparison.

I drive L37’s, LD8’s and the LC3 4.4 supercharger almost everyday at work. My L37 performs like an LD8. I ran a compression test and I think it’s low it should be around 175 to 180psi. I have 150 psi. Another thing, I can run 87 octane on a hot day and get 0 spark knock, the knock sensor activity is 0 too. I used to get spark knock before I had to run premium but the car would fly.

I’m down to checking the following:
1. The cam timing could be off at the crank
2. The cat could be restricted, but I put a vacuum gauge on it and it does not drop to zero as I bring it to wot.
3. Wrong cams ???? maybe?
4. A low compression engine. I hope not I am still working on the matter. Im going to pull a valve cover and camshaft numbers.

This I know for a fact there was a period of time were the N* plant in Livonia, Mich built many engines with the cam timing off at the crank. This engine could be one them I don’t know I wish I could get build dates. In 99 the PCM could not detect a cam / crank correlation problem so there would be no dtcs, a very hard problem to diagnose.

I am working on my car with Northstar engineers at GM they have driven my car and agree with me, it feels like an LD8. The L37 should make power at 4K mine does not. It feels OK from a stop ( but I know I lost a little low end too) and its flat at freeway speeds.

I check the calibration level, its an up level 130 mph L37 cal – OK, Fuel pressure OK, plugs and wires new OK. I removed the throttle body and cleaned it inside and out and cleaned the MAF, No changes. NO codes, all the data on the tech2 looks good including 43 degrees of spark advance.

I feel like selling the car, I bought an L37 because I wanted the performance of an L37.
Sorry for the long winded post, but I’m pissed, it would have to be my own car that we can’t figure out. With a 3 year old running around and my wife working nights I have very little time to work on it.

Thank for asking! it felt good to get that off my chest,

Frank T

davesdeville
09-23-06, 04:48 AM
I'd still throw it on a real chassis dyno and compare it to other L37s. Especially before I put money and time into diagnosing a problem that could very well be in your head. I know you're thinking "it's not in my head," but it's worth a check.

FrankT
09-23-06, 09:26 AM
I'd still throw it on a real chassis dyno and compare it to other L37s. Especially before I put money and time into diagnosing a problem that could very well be in your head. I know you're thinking "it's not in my head," but it's worth a check.

Dave,

Thanks for your guidance. Let me run this by you. A 96-99 L37 should be a premium-burning engine. My first engine would spark knock on regular 87 octane fuel during hot summer days, the engine had plenty of pulling power at freeway speeds so using premium did not upset me.
Now this engine is a new long block, the numbers on the engine say its an L37.
I have almost no power on at highway speeds now, the engine response is very flat. I can run 87 octane on a hot day with 0 spark knock. I monitor the knock sensors with the Tech2 and knock sensor activity is 0. Spark Advance is normal about 43 degrees.

What do you make of this? I can understand why you would say it might be in my head, that’s why I had other N* engineers drive my car.

My car is not allowed in any of our garages, if it were I would write a work ticket on it and let them tear into it.

Your thoughts please? Anybody’s thoughts?
:confused:
Thanks,

Frank T

eldorado1
09-23-06, 09:44 AM
Like I mentioned before, check the cats.

Whoops, gotta learn to read first.

The compression test sounds pretty normal to me.

yeah, I'd say to get the stampings off the cams. You should be able to look them up, if not I think I have a set of both L37 and LD8 cams here...

djb25
09-23-06, 10:33 AM
:

This I know for a fact there was a period of time were the N* plant in Livonia, Mich built many engines with the cam timing off at the crank. This engine could be one them I donít know I wish I could get build dates. In 99 the PCM could not detect a cam / crank correlation problem so there would be no dtcs, a very hard problem to diagnose.

Frank T

This is interesting. There has to be a way to check cam timing, right? I would look in my service manual, but it hasn't shown up yet (USPS lost it, of course).

Keep us updated on the search, I'm going to start looking into other possibilities as well.

Any idea how we could find out the build dates of the engines with the incorrect cam timing?

- Damion

dkozloski
09-23-06, 12:23 PM
A quick cam timing check that works for almost any motor is: Pull a valve cover. Position the piston in any cylinder at TDC at the end of the exhaust stroke/begining intake. Use a dowel down the sparkplug hole against the head of the piston to do this. The intake and exhaust valves for that cylinder should now be open an equal amount. It's rough and ready but will show if you are off a tooth somewhere. I've done this hundreds of times.

dkozloski
09-23-06, 12:29 PM
For a quick compression check: Pull a valve cover. Disable the valve actuating mechanism. Position the piston at TDC. Through sparkplug hole fill the combustion chamber to the bottom of the threads with clean oil using a graduated beaker. Position the piston at BDC. Fill the cylinder and combustion chamber through the sparkplug hole to the bottom of the threads using a graduated beaker. Do the math. I've done this many times.

djb25
09-23-06, 07:12 PM
Thanks for the tips dkozloski. Hopefully I'll have the chance to do this sometime soon.

My car does run pretty well, it just doesn't run the way I thought that it would. Timing would definitely explain things... and make me feel a little less insane!

Anyone else know anything about these mis-timed '99 motors?

- Damion