Still cant get it to run right

[montecarlofast]

So I still am having the same problem with my GN. I am pulling up a code that the TPS sensor is an open circuit. I have sweep tested it, (first one was new from Auto zone) Sweep resistance test was just fine. still doubted it so i bought an orginal AC delco. same code. i tested resistance of the wires, tested for short to ground, and ground at the ecm its all fine. why else would this code come up? I have also tried 2 ECMs with 2 engine and injector chips. as well as 2 mafs. Basicly the car will not start and run unless i trigger the injectors to squirt fuel before I start it. so its like a primming issue. and it barely runs. all sensors are new and the moror is stock. HELP! thanks

 

[notacarlo]

How are you "triggering" the injectors to fire prior to startup?

 

[montecarlofast]

with a power probe I throw ground through the trigger wire at the ecm.

 

[notacarlo]

So you are saying the injectors are not firing at start up, you have to physically over electrically trigger them.

Well, lets see. What controls injector timing and will not allow the car to start or even not run well?

If you are looking at the tps as the cause of the no start, you are looking in the wrong area. Now poor idle, whole different story.

Start with the engine fuel issue at start up first.

Is the cam sensor set correctly?

 

[notacarlo]

Is your fuel pump priming at key on?

Jump your fuel pump to run prior to start up and then try it. (without triggering the injectors)

 

[notacarlo]

If the above works, replace the fuel pump relay and move on to the TPS values and stumbling idle.

 

[montecarlofast]

fuel pump is priming. I have it selectable on a 40amp relay of my own. fuel rail has pressure (have guage) injectors are good (had them flow/tested) cam sensor should be fine. (Jace of Rjc racing set it for me) im getting one code on my OTC scanner and its open TPS circuit. but when i use the data stream part of it I can watch the voltage change on the display when I move the throttle.

 

[notacarlo]

You said during the sweep you saw the correct values...what were the values from closed to WOT(.42-44 to 4-4.2ishv)....no dead spots?

 

[notacarlo]

I suspect some type of ground issue. Still thinking about it.

 

[montecarlofast]

I have a bench top meter that goes 5 decimals points before the number. My TPS is good. no dead spots at all. and I can see it gradually go up in voltage as I depress the peadal

 

[pajo]

what do you know about the engine mechanically - is it sound - no wiped lobes etc ,jumped chain etc.

 

[montecarlofast]

it is all new. i rebuilt the motor but i am pretty sure it is all put togeather correctly

 

[RegalT-type85]

Is the injector harness grounding somewhere? check all your wires having to do with fuel injection/timing.

 

[pajo]

If you believe that mechanicaly is sound when was the last time you saw it ran and how did it run so another words what happened before it died.?

 

[Chuck Leeper]

Engine's been out.. did you check the grounds on the back of the pass head? Pinched in the trans/block face?

Does the pump restart after the prime cycle, when U R cranking the engine? Pump should come back on once the ecm sees 400rpm.[I think it's 400].

 

[montecarlofast]

i have the pump on a 40amp relay off a switch in the car as well. the fuel rail shows presssure for sure. the grounds are all grounded and grounded to the frame with O gauge. and then grounded with o gauge in the back (batteries in the back) injectors have 12v on the one side of the clips like they should. as for the grounding idea, i dont know on that. will have to check it

 

[Chuck Leeper]

Volts at the alt are?
Volts @ the batt + stud on the starter are?
Volts at the batt, + to - posts and then + to - on the frame is??
How is the alt wired to charge the batt?

Look herer.. Maybe find something....
http://books.google.com/books?id=3q...=9#v=onepage&q=automotive Ground test&f=false

 

[montecarlofast]

voltage is good. my resistance is low on all of my grounds, the alternator does charge. and when i put my battery charger (300 amp) and unhook the charging lead on the alternator it does the same thing. I hate this car. i can get mitsus to run like clockwork but 1980s gm tech is kicking my ass. what a world we live in. ha ha

 

[pajo]

hope

dont loose hope - it is usually something simple but you just cant see it.Keep on diggin at it and you will find it .I was tracing "car runs like s..t " for days untill I found bad mas sensor that did not give out codes and idled beautifully..

 

[gnray76]

Im with chuck here, trace the pink w/ black tracer wire from inj. harness, then it splices at the oil press. switch, then to the fuel pump relay, can also check ground wire off FP relay which is black w/ white tracer. but do check grounds at back of pass. head, and from block to firewall.. no matter how many times you look at it something will pop up.
HTH
ray