No idea what this problem is

[kdick91]

I posted this before in the fuel section, but now I'm starting to think I have an electrical issue and have beating my head against a wall for days. Here is what's happening. When I leave my car more than 30 minutes, it has a hard time starting (even after priming fuel system 5 or 6 times), idles bad, then runs like a champ. I can cut it off immediately then fire it right back up though. It did throw two codes, P0200 (Injector circuit malfunction) and P1635 (5v reference circuit). I am thinking it is a bad ground SOMEWHERE (I checked the back of the head and that one was good) and I am at a total loss. So any input at all would be amazing! Again, sorry for the double post, but I don't think it was in the right section to begin with and I feel it could get more attention here. Thanks so so so much in advance!

[69lemansguy]

if you are throwing a injector circuit code, could you have a bad injector? i dont know for sure jsut giving ideas.

[ShevrolayZ28]

Check your fuses?

[kdick91]

OK. I got a fuel pressure gauge and monitored it all day. It is EXACTLY where it should be. When the car is off, it never dips below 30PSI. Still extremely stumped... Could all of my injectors be bad?

[cody161]

ohm all of your injectors after the car has been setting for a while, write down all of the recordings. go drive the car and make sure everything under the hood gets really warm, then re ohm your injectors, watch your forearms as everything will be HOT. see if any of them are way off from the original recordings.

[kdick91]

Could one bum injector cause the car not want to start?

[kdick91]

So I may have figured it out.

I replaced the TPS, waited two hours, and it fired up just fine!

Weirdest thing I have ever seen in my life.

But I'm gonna wait till tomorrow and see what happens.

All the injectors ohm'd perfectly, so good thing I didn't drop anything on new injectors!!!

Thanks for the help.

Any more input is greatly appreciated.

[kdick91]

Fired up perfect this morning! But it had a hard time idling, but eventually smoothed out. Maybe that fixed it?

[69lemansguy]

another idea, maybe clean the MAF? maybe even some throttle body cleaner.

[LS6427]

Originally Posted by kdick91

So I may have figured it out.

I replaced the TPS, waited two hours, and it fired up just fine!

Weirdest thing I have ever seen in my life.

But I'm gonna wait till tomorrow and see what happens.

All the injectors ohm'd perfectly, so good thing I didn't drop anything on new injectors!!!

Thanks for the help.

Any more input is greatly appreciated.

Just proves once again how some PCM's will throw a code for something and some PCM's won't. Mine doesn't throw codes for bad 02 sensors, bad crakshaft positon sensor, bad TPS, or bad IAC.

.

[kdick91]

Well it is still throwing the 5v reference circuit code...
And it started first try today, but idled so bad it killed it fell on its face.
Could it be a bad MAP sensor??
After resetting the PCM it started and ran great.
So clueless here.

[VoggsStage1]

I know this is prob the first thing u did but check the Ground cable to the BATT. i had mine loosen up and cause hard starts and idling issues as well, no SES tho. Also did u calibrate the TPS and adj it watching data list to make sure PCM is getting correct value at idle, again at WOT? Having an issue with the 5v reference could be a bad PCM issue also, most likely wiring tho.

[kdick91]

Originally Posted by VoggsStage1

I know this is prob the first thing u did but check the Ground cable to the BATT. i had mine loosen up and cause hard starts and idling issues as well, no SES tho. Also did u calibrate the TPS and adj it watching data list to make sure PCM is getting correct value at idle, again at WOT? Having an issue with the 5v reference could be a bad PCM issue also, most likely wiring tho.

The PCM was just replaced. Ground to batt is a-ok. And it goes WOT just fine, so I'm guessing TPS is fine (just replaced also). Appreciating the input guys!

[Onemeanbird]

Sounds to me like you have something shorted out taking away your 5v reference. Any number of sensors can do this and usually wont set a code. Easiest way to find it sometimes is to start unplugging stuff. Not just randomly if you have access to a wiring diagram then you could look at what sensors are using the 5v ref. while the car is messing up start unplugging different sensors and see if it clears up do it one at the time and if it clears up when you unplug something chances are thats your culprit or you something along that part of the circuitry.

[kdick91]

Well based on the DTC, it is circuit 1. This can either the MAP sensor or the TPS. At least that is what it says on GearChatter.

[breze84]

Could be bad injector, bad fuel filter, bad sender unit.... Who knows, it could even be a fuse.... When you turn the ignition on and the pump primes, if you open your hood and push the valve in on the fuel rail does fuel jet out????? Not a trickle but actually jet out....

[kdick91]

I checked with an actual fuel pressure gauge and it reads perfect (yes, I know the values and they are all good). All the injectors had perfect ohm readings and the fuel pump and filter have both been recently replaced.

[breze84]

Hmmm Hard to say without actually looking at obviously.... All your fuses are good right, I assumed you checked all the grounds... you could have a short in a wire somewhere which im pretty sure you thought of.... What mods do you have and or any kind of tune????

[kdick91]

I have a tune by Shaner of S2 Performance, P&P tb, air lid, LTs and ORY, LS6 manifold, and I recently replaced O2 sensors, TPS, Oil pres, spark plugs, fuel pump, fuel filter, and PCM. I checked ALL grounds (I have a sheet of all the grounds) and most wiring diligently. I am checking the injector circuit per my Chilton and with a NOID light in the near future.

[breze84]

Is it a mail tune or actual dyno tune??? Mail tunes are trash.....