ACCOBRA

I have a new L92 engine in my AC Cobra Replica. It runs but it backfires when you throttle max and its having problem with acceleration also with full throttle. Sounds like its choke when full throttle and there is not that fast respone. What could be the problem? I will do a diagnostic test on friday.. If anybody can help me I really appreciate it!!

Thanks
Henning

Old Geezer

iTrader: (3)

When you test it, can you pull/post some datalogs??
Fuel pressure is?

ACCOBRA

Im using speartech ECM and wiring harness. a walbro 125psi fuel pump with corvette fuel regulator 58psi. I will let you know how the diagnostic test goes.

racecar

Check for codes set in the computer.
What program do you have, has it been tested. Where is the timing set for over 3000.
If this is an aftermarket computer and your program is not set for this motor, you may need a lot of tuning to the VE table with a wideband O2.

ACCOBRA

It is a orginal computer for the L92 engine (E38). With both MAF,O2 sensors.

ACCOBRA

I'm also having some problems with the idle/response. When you rev the engine up it takes a second or two before you have normal idle again. This is a litle bit disturbing when you shift from first to second gear, you nearly jump forward..

edgz06

Make sure you have the correct reluctor wheel installed on the crank for the PCM you are running.

If you have a 58x wheel with a 24x computer (or vice versa) it will run like that.

ACCOBRA

But i have a original L92 engine with a custom harness that using original PCM for that engine. I'm asuming that with "reluctor wheel" you mean the crank sensor? Could the PCM need some fine tuning?

edgz06

The reluctor wheel is pressed on to the crank it is what the crank sensor is reading to determine crank position.

When you say "original L92" what does that mean? Did you get the L92 from a donor vehicle or was it built from scratch? If it is from a donor vehicle, did you get the PCM from the same vehicle?

How are you tuning it? Is it still DBW or cable TB?

ACCOBRA

It's a new crate engine with a custom harness from speartech. What I know it shouldn't need any fine tuning. I will do a diagnostic test on friday at my friends workshop. Hopefully there is something wrong with the codes. At least I would know where to start looking.

ACCOBRA

I have done the diagnostic test. One error code MAP sensor bad. The MAP sensor was broken in two pieces on the manifold. I ordered a new one nad glued the broken one. I have still problems with bakfire over 3000rpm. Does anybody know if its normal with delayed idle? When I throttle it takes a second or two before the idle goes down to normal again? Is this adjustable?

smokinHawk

iTrader: (48)

check your plugwires / coil pack wires, that screwed me up when i put the coil pack wires flipped.

ACCOBRA

but if something was wrong with the one plug or one coil the engine wouldnt run smooth up to 3000rpm and then backfire?

smokinHawk

iTrader: (48)

mine would run smooth but backfire at times.

ACCOBRA

did it also choke when full throttle? My engine choke when I full throttle but I have full fuel pressure at all times. I will check all my plugs and coils tomorrow again for the third time

ACCOBRA

tripple checked all the plugs. 58psi fuel all the time but it still chokes when I full throttle.

ACCOBRA

About the reluctor wheel.
edgx06--> "If you have a 58x wheel with a 24x computer (or vice versa) it will run like that" . I have a L92 engine=58x wheel and an E38 ECM=58x computer... So it can't be any problem with that. I have been to two larger workshops now and they couldn't do more than see that there were 2 error codes. I think I found one workshop that could help me that sells Cadillacs.
.

Old Geezer

iTrader: (3)

The tuner should be able to datalog the system, and see where the problems are when reviewing the logs..If all they are doing is scanning for codes, there's not much point in that.
Datalogging and capturing the frames at the time the failure occurs is going to be pretty much the way to identify what's going on..
Posting the tune files could also help.
EFILIVE would be a good investment. That way you can do all the above, and be able to diagnos and tune on your own.

ACCOBRA

EFILIFE would be nice but not cheap.
FlashScan V2 Stream: S-E38 - 2006-2009 Gen IV (E38)
Price: US$2,495.00

When I'm at the workshop I will try to save the files and upload them here.

dfe1

ACCobra-- In what part of Sweden do you live?