CR Dyno Troubles

GSM-01

GSM-01

Can turn wrenches
Joined
Apr 14, 2007
Messages
1,481
I have been trying to figure out what is going on with a few trucks and its really got me stuck. I guess I should fill you in on the situation.

A couple weekends ago we headed up to the Belle MO pull because it was a dyno and pulling event. John from Floor-It was there with his dyno and alot of trucks were jumping on it. When it came to one of my buddies, Roughy, jumping on the dyno we had an idea of what the truck "should" have. John put it on the dyno and ran it through once. 500 and some odd hp. Not bad for a CR but we knew it should have been much higher, well into the 700 range. We thought maybe it was just a fluke run. So this time we threw the nitrous at it.... It came out less. Not happy. John was stumped but said its normal with some of the earlier common rails in that they just do not like the dyno. The ABS light was on for all 3 runs and the third run showed the same results as the second as we threw the nitrous on it again. The truck just isn't loading the rollers as it should be but and we know it has something to do with the ECM with the ABS unit. The truck should have way more power to it but we think something is throwing the ECM off since the ABS light keeps gettin thrown everytime on the Dyno. Chris put his CR up on and rolled 662 (only 6hp off his best of 668) so we knew everything was ok and we all trusted John with what he had to say.

Does anybody know why some of the early CRs are not dynoing as they should. This is not the first time we have run into this problem and though the truck was not as built as the one we had at Belle but with the modifications on the other truck, we should have had more than 415hp when pump, injectors, turbo, etc were all on it. Is there a modification that is through these trucks off? I don't want to throw out everything in detail of what Roughy has as I don't want to open things up with that truck but to give you an idea its twined, injectors, pump, downloader, etc, the whole nine yards as it is his pulling truck and nothing else. I have been trying to put the nail in the coffin for why his truck and a couple others just don't want to dyno. Any ideas? Anything would helped lead me to some sort of conclusion at this point.

TK
 
On the newer vette's, traction control and the other electronic stability control must be disabled. Think that's happening with these?
 
unlikely as there isn't any such technology on our trucks (yet).

However, the fact that the rear wheels are spinning at 100mph and there is no ABS singles being triggered from the front hubs may have something to do with the ECM getting confused but that is rather odd

Try pulling the ABS fuse on the next dyno run.
 
JasonCzerak said:
unlikely as there isn't any such technology on our trucks (yet).

However, the fact that the rear wheels are spinning at 100mph and there is no ABS singles being triggered from the front hubs may have something to do with the ECM getting confused but that is rather odd

Try pulling the ABS fuse on the next dyno run.
Click to expand...

The ABS light is on when the runs are being done, showing that the units are working. Wouldn't pulling the fuse just cause the ABS system to trip automatically and still have the same problem or would it more or less override the system to where it won't work at all? I assumed that when pulling the fuse it would just get us back to where we are at with the ABS light on.
 
When I dynoed my 03 I had removed the abs fuse. I removed it cause the stock speed limiter.
 
GSM-01 said:
The ABS light is on when the runs are being done, showing that the units are working. Wouldn't pulling the fuse just cause the ABS system to trip automatically and still have the same problem or would it more or less override the system to where it won't work at all? I assumed that when pulling the fuse it would just get us back to where we are at with the ABS light on.
Click to expand...

should just disable it and bypass things.
 
it will make the ECM think the abs system is malfunctioning......thus will ignore the abs signals from the 4 corners.
 
Thanks guys. Been trying to figure it out and didn't think that would be the simplest way but maybe it is.
 
The ABS light is common while on a dyno. The front tires are not moving yet the rears are hauling butt. This will cause the ABS system to believe their is a failure in the system. It should not change output to the rollers.

I am not sure how the truck is programmed, but you may want to double check there are no limiters set for EGT, boost etc.

Aside from that, the only other issue I have seen with CR's are draining the rail, or weak CP3's.

What did the curves look like?
 
I agree. I prefer those curves ofver graphs any day.
 
GSM-01 said:
I have been trying to figure out what is going on with a few trucks and its really got me stuck. I guess I should fill you in on the situation.

A couple weekends ago we headed up to the Belle MO pull because it was a dyno and pulling event. John from Floor-It was there with his dyno and alot of trucks were jumping on it. When it came to one of my buddies, Roughy, jumping on the dyno we had an idea of what the truck "should" have. John put it on the dyno and ran it through once. 500 and some odd hp. Not bad for a CR but we knew it should have been much higher, well into the 700 range. We thought maybe it was just a fluke run. So this time we threw the nitrous at it.... It came out less. Not happy. John was stumped but said its normal with some of the earlier common rails in that they just do not like the dyno. The ABS light was on for all 3 runs and the third run showed the same results as the second as we threw the nitrous on it again. The truck just isn't loading the rollers as it should be but and we know it has something to do with the ECM with the ABS unit. The truck should have way more power to it but we think something is throwing the ECM off since the ABS light keeps gettin thrown everytime on the Dyno. Chris put his CR up on and rolled 662 (only 6hp off his best of 668) so we knew everything was ok and we all trusted John with what he had to say.

Does anybody know why some of the early CRs are not dynoing as they should. This is not the first time we have run into this problem and though the truck was not as built as the one we had at Belle but with the modifications on the other truck, we should have had more than 415hp when pump, injectors, turbo, etc were all on it. Is there a modification that is through these trucks off? I don't want to throw out everything in detail of what Roughy has as I don't want to open things up with that truck but to give you an idea its twined, injectors, pump, downloader, etc, the whole nine yards as it is his pulling truck and nothing else. I have been trying to put the nail in the coffin for why his truck and a couple others just don't want to dyno. Any ideas? Anything would helped lead me to some sort of conclusion at this point.

TK
Click to expand...

I have never actually experienced the ABS problem on the dyno with any truck, but it seems his truck might be in LIMP MODE or battling torque mangement. I would suspect the large difference between signals from the front ABS and the VSS signal being seen by the ECM. Disable the ABS and load the truck by using the boost gauge and the tach.$.02
 
IMO, the ECM does nothing with the ABS, It just doesnt care, have you considered the RWAL was pulsing the brakes to correct the ABS signals?
 
DavidTD said:
Bob, the curves in your Avatar sure have a nice shape. :shake:
Click to expand...
-----------------------
Yeah Bob,.....NICE AVATAR!!!!!:rockwoot:
 
I know that dyno is right on but his truck has always been an odd ball IMO I know his isn't draining the rail either. But the ABS light come's on everytime he gets on the dyno I think that is part of the problem.


Bob I need to get my hands on some of these new tunes........
 
ISBeINSIDE said:
IMO, the ECM does nothing with the ABS, It just doesnt care, have you considered the RWAL was pulsing the brakes to correct the ABS signals?
Click to expand...

VSS is tied in with the ABS. VSS is tied in with ECM and Torque converter lockup, so your sure it is not causing a problem?
 
sootman said:
VSS is tied in with the ABS. VSS is tied in with ECM and Torque converter lockup, so your sure it is not causing a problem?
Click to expand...

you guys mentioned this specific truck is an 2003, if so check to see if you still have the JTEC PCM on the passenger side fire wall, if so then the VSS is an input buss to the ECM, JTEC PCM, and an input/output from the ABS CAB to the PCM. the ABS output is an input to the PCM, not ECM, the ECM only uses it for load calculations and engine overspeed situations. The PCM would use the VSS inputs from the ABS CAB for TCC and OD. That said the PCM cannot put the ECM into a Derated state. Clear as mud!
 
Chris Blevins said:
I know that dyno is right on but his truck has always been an odd ball IMO I know his isn't draining the rail either. But the ABS light come's on everytime he gets on the dyno I think that is part of the problem.


Bob I need to get my hands on some of these new tunes........
Click to expand...

Chris, good to see you back. You probably know a bit more about Roughy's truck than I so it might help the situation. Roughy wanted me to dig deeper. The dyno graph looked fairly normal to me, nothing out of the ordinary but John said you could tell it just wasn't loading the dyno like it should.

Bob, I'm with the rest of them, I'll watch those curves any day over a dyno!:rockwoot:
 
Its been my experience that the 03/04 engines have always had issues making good reliable power. I have no doubt that I would be 650 to 700hp with a 04.5+ and newer. My truck does the same ABS issue on the dyno. Always has. I don't believe it has effected anything with the dyno but thats my opinion. If you are saying that the truck should be 700+hp with all the mods because a 04.5+ and newer CR is doing so that would be mistaken.

The only way I have been able to make decent power with the 03 motor is by stacking boxes which makes me sick because people with a 04.5+ newer are doing well over my numbers with 1 box.

I'd be curious to know what he is running (if you want to pm me) to see how much in reality he is with the parts he is running on that engine. I'd be happy to share my experiences with parts and blah blah blah.
 
You must log in or register to reply here.
Back
Top