Silvrfsh

iTrader: (2)

So threw a new engine in a 98 fbody, Gen4 with the cam sensor up front 1x, 24x callies crank, and only under WOT conditions it was hit what almost seems to be an a false rev limiter, if you bring it past ~5800 (I used 6000rpm) and then go WOT you can carry it all the way out, highest thus far as been 7700rpm and it was pulling fine.

Any ideas on what would cause this? Swapped out both cam and crank sensor with known working good ones and new ones as well. Exact same symptom.

Thought the 98 ECM wasn't keeping up with the new motor and threw a dominator at it with a new Holley harness, same exact issue (although I really didn't want to spray it on the 98 ecm anyway... so I needed it anyway is what I keep telling myself ). Only difference being with the 98 ecm it would shoot a fireball the size of texas out the tailpipe when you hit 5800 and then die whereas the dominator will just stop fueling and you go 0% throttle and it recovers to idle.

I moved the cam sensor wires (Katech extension harness w/ knock for Gen3 to Gen4 swaps) further away from ignition wires, no real change.

Verified harness grounds to the back of each respective head, and that they were tight. Engine to chassis grounds are good.

I'm at a loss for what would be causing this; never did this with the old LS1. Again only at WOT.

subeone

iTrader: (5)

try using a different battery. Had the issue happen to me where i could see the INJ ms would dip to about 3 ms from what used to be 14ms or so. Changed the battery and it fixed the issue. Give it a try, won't hurt anything.

Old Geezer

iTrader: (3)

That happens when you "throw **** around"....
Try data logging??

Silvrfsh

iTrader: (2)

There is a good example of what is going on.


And again... as stated in the OP, if you bring it past 56-5800 rpm and then go WOT then it pulls as high as you like.

joecar

Wild guesses:
- spark plug wires are not emi-suppression type.
- crank reluctor comes loose.
- crank end play is out of spec.
- TP sensor has dead spot.
- MAP sensor has dead spot.
- MAF sensor has dead spot.

The GM PCM has some pids (STATExx) that may indicate reason for cutting fuel.

Silvrfsh

iTrader: (2)

- spark plug wires are not emi-suppression type.
They're MSD 8.5mm and didn't cause this on the old LS1... idk?

- crank reluctor comes loose.
I've heard of Callies having these issues, but the engine builder states that the reluctor was spot welded together, but remained pressed on.

- crank end play is out of spec.
Measured to be .005" 2 weeks ago, so that should be within spec. Also I looked through the crank sensor bore and verified the reluctor in center, have pictures of that and the old LS1 bore if anyone would be interested in me posting those. Only notable difference is the original LS1 reluctor looks like its pressed together tighter than the Callies piece, engine builder insists this is fine.

- TP sensor has dead spot.
I haven't checked this yet, although this is probably the only sensor I haven't changed at this point, wouldn't a dead spot show up on the data log? And it would have to be at 100% only? Idk anyone else have thoughts on this one?

- MAP sensor has dead spot.
Have used multiple LS1 maps, including the original to the old LS1 which was working great prior to a piston failure. Maybe its time for a GM 3 bar for future growth? haha

- MAF sensor has dead spot.
Sorry, should have specified. Both the old LS1 (which did not have this issue and could shift at 6500 religiously WOT) and the new Gen4 setup were both speed density. No MAF present.


the GM PCM isn't hooked up anymore unfortunately... can I pull that info off a bench?

joecar

^ this may be a problem.



BTW: MSD Superconductor 8.5 mm wires are ok.

Silvrfsh

iTrader: (2)

Original '98 24x wheel






New 24x wheel that came installed on the callies crank


I don't know... thoughts?

Silvrfsh

iTrader: (2)

Does anyone have any input as to whether or not Holley's EFI uses the crank input for fueling control?

DAMartin

Did you ever find the problem ? I am currently experiencing a similar problem on a stock bottom end LS1 with mods including heads, cam, intake, headers. It runs great till it starts hitting high RPM in 3rd gear then just falls off - get off the pedal and it picks up a idle speed.