RyanClemens

Basic info:
04 GTO engine in a Mazda FC RX7.
SD tune. No 02s.

Engine will start and run for a minute or two. It will not react to small throttle changes, and will die upon large throttle openings.
PCM is flashed using HP Tuners and is Speed Density. Throwing no codes. Spark on all 8 is confirmed, as is signal at the injectors. I clicked the injectors over with 12v and ground just incase they were sticky. Fuel pressure is rock solid at 58psi during cranking and while running. Gas is new. Plugs are new. I pulled them and they were all heavily sooted, but sooted evenly and were dry.
Checked MAP, Cam, and Crank sensors with multi meter, they all ohm out correctly and are seeing the proper voltages.
I added grounds to the engine just to make sure.

I don't have any vacuum leaks in the engine. I pulled the valve covers and everything is as should be in there and all the rockers are rocking. The reluctor wheel on the crank feels fine and undamaged.

One thing I thought of was my lack of the idle valve on the throttle body. My engine didn't come with one, so I just made a block off plate for it. I have a friend with an LSx and he told me he has run the car with the idle valve unhooked, so it seems like it should be fine, but I just want to make sure.

I have been working on this thing for 3 weeks and have found a few small issues here and there, but none of them made any difference in how the engine reacts to throttle. I have an obd scanner thing and all of the sensors that I can look at are operating fine.

I am about at my wits end with this thing. The car has been ready to race besides the engine issues for the last month. I am hoping one of you has some insight on this issue!! Sometimes it just takes another mind to see something you are not seeing.

Thanks for looking,

Ryan

350SS

iTrader: (38)

What transmission are you running and what trans segment in the HPT file?
Have you used the scanner to check that the rpm, map and tps readings are correct?

RyanClemens

Transmission is a GFORCE. All codes and such were removed that had anything to do with a transmission.

MAP, and TPS have been verified.

RPM works on the scanner, but the PCM threw a code regarding the tach output wire. Cleared the code, hasn't come back. Don't have a tach in the car to check to see if the output is working or not.

thanks

LS1FBIRDTA

is every thing wired up right, do you have the vss hooked up or bypassed in the pcm? I've heard alot about stalling probs @ idle due to impropper/missing vss sig. if you have no tach. then that tells me this could be your prob. unless you know for sure that its either suppl. the correct signal or has been tuned out of the pcm.
thats my guess any way, I have the same ls1 in my '91 & I have the vss tuned out right now for 700R4(furutre t56 upgr)

350SS

iTrader: (38)

a gforce what? manual, auto...

allright, after googling i guess manual. are you running a tune for a t56 trans?

Spike-Z

iTrader: (2)

I have the same problem. Ordered new injectors, they should be here pretty soon. Im suspecting clogged injectors. They all ohm correct, they all receive pcm signal, coils are all firing. The engine ildes pretty good actually but has 0 power. I barely can go over 1k rpm. Mine is also t56.

350SS

iTrader: (38)

not sure if ryan's problem is this but Spike-A might want to check this out

https://ls1tech.com/forums/conversio...-1500-rpm.html

RyanClemens

I brought the car into the tuner who flashed it, and he knew about the transmission and everything that I had removed from the engine/harness.
I would assume he got rid of anything to do with the VSS in the computer, but I just emailed to make sure.

Engine harness got torn down today and everything is good. Wires ohm out, pins are solid in connectors, ecu plugs are ok, etc etc.

I figured out I had the AIC blocked off wrong, so I fixed it and now the engine will rev a bit and idles better, but there is some other underlying issue that is still making the car run like crap.

Could this be as simple as needing a crank relearn? Or the CKP sensor malfunctioning?

Thanks for your help guys, I appreciate it!

LS1FBIRDTA

if the crank sens. was bad you'd get codes & if the motor starts at all then the crnk sensor is probly good, could be a crnk re-learn thing Idk, but mine ran kinda rough at 1st once I got it runnin & then just cleared right up on its own & runs flawless ever since!

68 impala

I am having a very similar problem, and it is ddriving me nuts. Only idles, sometimes stalls out, no pedal response at all and no codes being spit out.

http://www.youtube.com/watch?v=IH19cpgyNhw

MikeyZ

iTrader: (20)

what year pcm are you running its possible you have a 58x reluctor and a 24x pcm