Ok, so I went to the local dragstrip the other night, made a pass....all was well. (1/8mi 1.76 60', 8.19 @ 83.55). Happy, I went to make another pass, came out of the whole, and i must not have had the shifter in gear all the way, regardless it jumped into neutral, and hit the rev limiter. I was pissed, but then once I pulled the car back into gear, (after the revs dropped), the car died. I put it in park, went to re-fire and it just turned over, no attempt to run. I towed it back to the pits, checked fuses, etc...nothing, had to flat tow it home.

I left the battery disconnected for 2 hours as well, nothing.

Today, I decided to do a compression test just to make sure I didnt bend any valves and all cylinders were between 165-190.

The car has spark on #1 cylinder (which I was told the crank trigger controls spark) and #3 (which I was told the cam sensor controls spark for 2-8), fuel pump primes up, and with the schrader valve depressed squirts fuel everywhere (cant find my damn fuel rail pressure gauge).

I checked the PCM ground on the harness using my mulitmeter, went positive side of battery to pin 72 and 76 and it showed 12v. When I turn key on, the injector plug shows 6ish volts and drops to 4ish volts when cranking if I use my mulimeter on just the injector plug. If I go pink wire on plug to chassis ground key on, i get 12v. Still nothing, I cant find a fuse popped, the PCM connects to a scan tool, which has nothing major in the code files.

Im lost, and I am hoping the LS1TECH community can help me out.

I got the car built as it is, which up til now has been a lot of fun.
1998 Trans Am
Stock engine
Hooker LT, ORY
Borla cat back
TCI Street fighter 4L60E
3500 stall
BMR torque arm
Tubular rear control arms w/ relocation brackets
Moser 9" 3.90 gears, 35 spline axles, Detroit Locker
295/55-15 Mickey Thompsons ET Street S/S on Race Star wheels skinnies up front with M/T tires

 

So now I get a P0601 code from the scan tool, which is a

INT CONTROL MODULE Memory Check Sum Error

According to the internet, the PCM is bad.

Funny thing is, I can get data streaming from the OBD2 fine, all sensors are present, shows cranking RPM's, shows timing being added, all the gauge cluster works.

Maybe it burned up the injector driver??

 

I would check the grounds. Also disconnect the battery and make sure it is fully charged.
If that doesn't fix it, then a bad PCM is very likely.
Unfortunately 1998 PCMs have become rare and therefore expensive.
If the '98 PCM is unobtainable you could repin the PCM connectors to use a '02 "411" PCM.
Hopefully it won't come to that.

 

Yeah, I thought a ground would cause my problems, but I havent found one thats loose yet. Going to a 411 is an option, but I rather use a Megasquirt and piggyback it onto the 98 PCM. Problem is, I cant trust this PCM.

 

I was able to borrow a fuel pressure gauge, and it confirmed that the rail is pressurized. Gauge said 50ish psi.

I sprayed some carb cleaner directly into the intake and the car, cranked it over and it stumbled, so I know its capable of running. The injectors are simply not firing.

I went ahead and checked the 2 PCM grounds on the blue plug, and they are showing continuity. Im seriously lost with this car. From my intense internet searches, I have found nothing concrete.

I realize the PCM grounds the injector to open it, and I know the 12v source is good, but the damn injectors do nothing while cranking, either bank. The INJ-1 and INJ-2 fuses are good and seeing 12v.

 

Maybe a vats problem? Just throwing it out there.
My buddy just dealt with the same thing in his 98 z28.
https://ls1tech.com/forums/pcm-diagn...-security.html

 

Reading post #5 I immediately thought of VATS too.
However, on a '98 PCM, the engine will fire for about 2 seconds before VATS shuts it down.

 

MRV, is that true? Im willing to try anything at this point. I want to confiem this PCM to be reliable to run my 4L60E and gauge cluster....and I really want to go with MS3 to run fuel and spark. I guess I can always soak the car in gasoline and flick matches at it

 

My earlier LS2 came with a '98 PCM in which VATS was not disabled. It would start, run for 2 seconds and shut down. I've seen other references to this behavior here. Don't know if the 411 PCM works this way too, but suspect it does.
Not sure what you plan on trying.

 

Well, I would determine my VATS resistance, and bypass it with a resistor. It would at least eliminate that being a possibility. Honestly, I may give it a couple more days of fartin with it, and I will make a decision on what system I will switch to. HPtuners will be at least $500, and I still should switch to a 0411 PCM. Then, I guess I could do a piggyback Megasquirt 3, which will be roughly $1000, and use the 98 PCM to control the trans and gauges. Or go full drop on standalone Megasquirt MS3-Pro and Microsquirt trans control....which is $2000+. I have some choices for sure.

 

Trying to piggyback two ECMs is a nightmare as some sensors are not designed to run two ECMs.
What do you expect to gain out of using the MegaSquirt ECM?

 

yeah, the sensors that cause issues (IAT and CLT) you just add them to the system, all the others you can share the signal wire. Megasquirt 3 has flex fuel capability, launch control, a bunch of I/O for boost control, 2 step, etc. and no CREDITS. The tuning software is $59. I am open to suggestions, and I would like to do this once. My intentions are to have a turbo 9 second street car that can scare my kids and wife with.

 

This may help:

Engine cranks but does not run

 

Ok, I have been busy trying to sort this car out. I purchased HP tuners Pro VCM suite, P59 PCM, flex fuel sensor and plug, and waiting on the 3 bar map to arrive. I went ahead and repinned my harness to the +99 PCM, plugged the P59 PCM in and now am searching for the next step. My goal is to have a 3 bar SD tuned car that has flex fuel capabilities. The learning curve is slightly steep on HP Tuners, so Im trying to wrap my head around it.

 

Sounds like excellent progress.
You are always welcome to post tunes and log file and ask for help.

 

Did you ever found what the problem was? I have the exact same problem, I've disabled VATS, and still injectors wont pulse.

Regards,

 

Hello, this link no longer works. Would you have another that can show me the same info? I have the exact same problem with 98 pcm. Only difference is that mine went bad after a reflash, and I tuned back the stock parameters, but it did not start again. Tks,

 

You're replying to a FIVE year old thread.....

 

The 98 PCM is hot garbage and last time I looked (because I needed one) there weren’t any left that passed QC checks. Even ordered 2 of them, I got called the following day from each company, respectively.

Best bet is an 0411 upgrade. You’ll have to repin it, but so long as you label everything it’s not terribly difficult. You’ll also need to lengthen some wires. Good luck.

 

Thanks ChopperDoc. I will order the 0411 today and re-pin the harness. My 98PCM stopped firing the injectors after an "Write Entire" with HP Tuners. Don't know if that reflass process reflashed it or if I messed something up... anyhow, 0411 accepts 3Bar MAP and I understand is a bit faster, so Re-Pining it is!.

Regards,