need help trouble shooting

[rkreigh]

this problem started out when I bought a set of stock injectors and a stock chip to hopefully pass tough VA emissions. I put in the injectors and the car ran really poorly and was cutting out after starting so I swapped back to the 72 lb injectors, car ran fine.

I ran it to the station, and the car started running really poorly, had to limp it back home (acted like it was running on 4 or 5 cyl)

well then it got worse, car would turn over and not start. I got a bit disgusted and the car sat for a couple of months. I put some fresh gas in it, charged up the battery and it ran fine again! I let the car warm up, tried to start it again, and it's back to firing and then run very rough and cut out

I checked that I have fuel pressure, tried swapping out the LS1 MAF with the stock one, trying a spare ECM, and checking connections to the coil pack/module no luck, car fires and immediately dies

I don't have any codes set, and am thinking this is a wiring problem.

I thought at first the CAM position sensor went bad, but since it fires here's what I'm considering but need some feedback on how to best trouble shoot

1. bad injector wiring harness. thought about putting a test light on each injector while turning over the car to see if it lights up. I've heard about "noid" testers but don't really know what the heck that is or how to use it. I do have a volt/ohm meter and a test light.

2. bad ignition module. car has a recent coil pack

3. bad wire in engine harness. this car is getting old, and the wiring is original, but that is probably beyond me

don't want to throw parts at it, any help or suggestions is appreciated!!

 

[Joe 1320]

Considering that by your description, it was running fine before you swapped injectors.

Any codes?
Are you sure the chip is not at fault?

if the chip is fine and now the car runs like crap even with the original injectors, I would suspect the injector harness has a bad spot. A noid light
( a light configured to plug into the end of the injector harness and flash when the injector receives a pulse) should be used to test at each injector.

 

[gnray76]

the starting and running like crap and dieing, sounds to be a bad map sensor...mine started that also before swapping out, the vehicle started and immediately dies w/ poofs of black smoke, the computer and injectors cant see being the problem? vacuum lines maybe?
joe explained the noid light...

 

[justin84]

Cam Sensor...Did you tamper with any grounds? Harness is possible. Can you get the car to run and see if all the injectors are pulsating?

 

[rkreigh]

thinking the injector harness may have a short in it as it's old and I've swapped injectors quite a few times

going to try the "noid light" trick and check each injector wire.

going to do the same thing to see if I'm getting spark

thanks for the tip on the MAP sensor, that could be it too.

where can I buy the parts? looking for the wiring harness, ignition controller, and cam sensor cap. I verified that the disk is turning.

thanks for the tips

 

[TurboDave]

the starting and running like crap and dieing, sounds to be a bad map sensor...mine started that also before swapping out, the vehicle started and immediately dies w/ poofs of black smoke, the computer and injectors cant see being the problem? vacuum lines maybe?
joe explained the noid light...

MAP sensor???? MAP sensor has NOTHING to do with engine/ECM operation in these cars. (unless it has been converted to speed density, which his hasn't)

 

[rkreigh]

thanks for the tips,

need to get the old buzzin half duzzin back on the street

 

[norbs]

If the coil pack is not 100% grounded it will create a poor spark. Make sure the bolts are tight and you sand the mounting ears to bare metal on the module holding bracket. You may have broken some grounds at the back of the head possibly also. Did you mix up any of the injector harness #s? If your getting spark it means the cam sensor is working, but sometimes they get loose inisde and the spark now is intermittent or the sensor it self goes bad,

 

[Scott Atk]

I would check the injector harness really well. Especially around the EGR valve.

 

[novaderrik]

check the wiring to the temp sender. mine shorted the two wires together once and it would do exactly as described- it ran great until it started to get warm, then it would sputter and die and not want to restart until it cooled off.. i was getting a little frustrated about the whole ordeal.. then i accidentally bumped the wiring to the temp switch when it was running like crap and it evened right out... what happened on my car was that the insulation on the wires shrunk a little bit, which left some of the copper wire exposed, which allowed the 2 wires to come into contact and make the ecm think it was always dead cold and make it run super rich. you might have bumped it when swapping injectors the first time, and that's why it started acting up then.

 

[rkreigh]

finally got the old buford back on the road and running STRONG

turned out it was the ignition module I was really surprised to find these part still available and put a new ignition module and coil pack on the car and it fired right up and ran as smooth as ever

now, back to getting the car looking good and BOOST A MUV

it's great to have the old T back on the road. I forgot how much fun this car is for an old tank. (gotten spoiled by the TT Z06 and put the old gal aside for far too long)