1g random no starts, starts when it wants to

[1gAWD92]

Hello tuners, i have looked in to this problem for the passed week now but havent solved it yet. little background: I took the car up to my bank park, go in to the bank, come back out to head home. But the car wouldn't start. this has happened once or twice before but it would start up after like the 3rd or 4th crank. This time not so lucky i get it towed and start looking for spark, and fuel. i have both. then decide to look at the injector voltage. i checked injector 1 and it was only getting 1 volt constant. i know thats not right.

Did some research and found that it could be the CAS. or a temp sensor. But here is the kicker! The car was siting for a day or two. so just for giggles i go to start her up. She starts right up and drives like a champ!

Im kinda stumped at this point, and the car has bin running good sense then. but im having a lack of power in first gear pulls. its like it will only pull when it wants to.
Any input you all have would be great.

-Bryce

 

[talonxgirl]

When it doesn't start, is it cranking? Or is it just dead? My car did something like this where it would start every other day, and it was caused by a shorted ignition switch, which also caused many of the other systems to fail, such as taillights, dash, and fog lights, and possibly coils, too. Mine was a slow progression that took me almost 2 years to find, because I thought random things were just breaking and didn't see a connection until it was fixed and everything came back on. I'm thinking you have a short somewhere in that wiring harness or something it connects to.

 

[1gAWD92]

It will crank and crank just wont start. all my dash lights work though.

 

[talonxgirl]

Okay. Well, have you checked the injector voltage since it started going good?

 

[1gAWD92]

no i havent. its got to be something im over looking.

 

[talonxgirl]

Probably is. It's always something ridiculously random that goes wrong with these cars. Are all the other injectors good? If so, it may just be the injector itself. It throwing up a check engine light? There's a thread on here somewhere with directions on how to check obd1 at home.

 

[1gAWD92]

no check engine light or anything. i only checked injector 1 when i had to get it towed. it only had 1 volt of constent power when i cranked the motor over. i have bin told that that CAS controls the voltage going to injectors 1&4. i havent found anything that backs it up yet though.

 

[steve]

On the turbo cars there is a injector resistor between the output of the MPI relay and each injector making up the power side. (on the non-turbo cars the injector is connected to the MPI relay for power directly.)

The ECU switches the other side of the injector to ground to fire it. If your seeing voltages that low all the time disconnect the injector and start working back from it to the battery until you find battery voltage. If unplugging the injector is enough then it's time to pull the ECU and get it checked. (Usually a good idea to start by checking the ECU on a DSM whenever it isn't starting)

 

[1gAWD92]

This is going to sound dumb but what does MPI stand for again? i forgot. What would be in volved to check the ECU? or just send it out to a pro?

Im glad i got a wiseman in here now. Have you heard of the CAS controlling voltage to injectors 1&4?

I haven't checked any other injectors just injector 1.

 

[govproperty]

mpi stands for multiport injection. Also, one way to check your ecu is to open it up and check for capacitor leakeage.

 

[1gAWD92]

thats right! what would the leakage look like or would i know it when i see it?

 

[govproperty]

It would look something like the one found in this thread.
http://www.dsmtuners.com/forums/newbie-forum/253120-capacitor-leak-repairable.html
But you would want to check around all three capacitor for leakage. Post some pics of it if you are not sure when you get it open.

 

[steve]

Have you heard of the CAS controlling voltage to injectors 1&4?

I haven't checked any other injectors just injector 1.

The CAS doesn't control the voltage to the injectors, it controls when the ECU fires the injectors.

There are failure modes of the two signals from the CAS where the ECU won't fire 1 and 4 or won't fire any.

 

[1gAWD92]

It would look something like the one found in this thread.
http://www.dsmtuners.com/forums/newbie-forum/253120-capacitor-leak-repairable.html
But you would want to check around all three capacitor for leakage. Post some pics of it if you are not sure when you get it open.

ok ill check it out when it acks up again. i just drove the damn thing to work this morning with no problems. hopefully it will start when i head home.

The CAS doesn't control the voltage to the injectors, it controls when the ECU fires the injectors.

There are failure modes of the two signals from the CAS where the ECU won't fire 1 and 4 or won't fire any.

Ok thanks for clearing that up for me. ill check for leakage when it desides not to start again.

ill get some pics as well.

thanks for all the help guys.

 

[1gAWD92]

QUICK UPDATE..... MARRY CHRISTMAS......... But on to more important matters I decided to pull the ecu out a couple days ago to check for EPROM and leakage from the caps. luckily im epromed and didnt find any leakage in the ecu, but as you can see from the pics. i have found coolant leaking from the heater-core im sure that played a hand in my no start problem. At first i really thought it was rodent urin! it smelled just like piss. after looking closer i could tell it was coolant. but look at the pics and tell me what you think.

-bryce-

 

[1gAWD92]

So i was coming home from the bowling ally late last night, and decided to take some back roads so i can get on it, and really drive the car. i hit 3rd and the check engine light comes on for 15-20 sec. then goes off, right after the light goes off the whole car shuts off. i tried to start her up again but no luck just cranked and cranked. so i left it there. and came back this morning and it started right up!. im having a hell of a time trying to figure out this problem

If anyone can help me out it would be greatly appreciated

 

[stars]

Late Posting I know...Since the check engine light came on the code is stored inside the E.C.U. Have some shop check for Engine Codes and have them write down what they are and post back. The leak I wouldn't think would cause the problem unless it drenched the entire inside of the E.C.U. I.m.o the board appears in mint condition. The bad is that your entire dash has to come out to get to the heater core. Remember to flush your coolant every 2 years whether it needs it or not to keep this problem from happening again in the future.

 

[1gAWD92]

Im in the process of doing the heater core now. if i didnt drop my phone today in the toilet at work today i would have posted pics.....pain in the @$$! As for the codes. im waiting on a DLC, and software to pull my codes----After i put my car back together