Resolved No CEL, No Startup HELP!

[VETTE_50_TH]

Went to drive my car couple days ago when i had a no check engine light in the start postition and when i went to start, just cranked and cranked and cranked. The Fuel pump starts up but the wierd thing is no check engine light. I read the manual and it said that if there is no cel, then a fuse could be blown or light dead. But i cant find that fuse and i still think that the car would run with that fuse blown. Also, the car ran fine the previous day that it didnt start. Where should i start and what could be causing this??

Need help immediately. Thanks in advance!

James

 

[deadly_raptor3]

I had the same problem with my 90 gs-t eclipse....i replaced everything I could find from.....cam sensor,coil pack, plugs, power transistor, starter, battery, wires, ground strap.....still have no start....i also checked the ecm for burn holes or anything weird but nothing ......have fire coming out of the wiring harness going to the coil but no fire coming out and everything is brand new......I am currently working on this problem and when I fix it I will post the answer......Also have checked numerous fuses and all checked out okay...

 

[VETTE_50_TH]

My car has started up for months without a slight hitch and now one day my CEL is gone and car doesn't turn over. Makes no sense, I wish there was some warning that came along, but it was out of the blue.

 

[schoffs4]

Check the mpi fuse near the battery

 

[VETTE_50_TH]

What does the MPI fuse do and where is it located?

Well its another day without out my car working,

The mpi fuse is fine, all the fuses are for that matter.

Checked the coil pack and seems to be working, but I still have no spark and check engine light when I start it up.

I defiantly have fuel cause I took the fuel rail off and fuel spilled out. Not fun. but no spark. What could be causing this?

 

[zimfro]

Vette,
Did you actually: pull the sparkplug, ground the electrode to the motor, and have someone else turn the key to verify the no spark situation? If so, how do you know the coil pack is working? I'm new, but I'm trying to understand the problem completely. Do you have any other details to give?

 

[bling5tatus]

Get a logger and pull the code.

 

[VETTE_50_TH]

Thats todays battle. Pulling that code if there is one. There is no check engine light, and codes are stored in the ecu. So if its not coming on, i hope its still holding a code for the problem. Yes i did ground the elctrode and the coil is fine because i took it out and tested it. So it could be the power transitor or a short somewhere. Hopefully not from my gm maf!!

We will see.

 

[remmargorp]

I am troubleshooting what appears to be the same issue.
I am pretty sure I have isolated the issue to the ECU.

In my case I was able to smell a burnt anti-freeze like smell. After testing all the spark plugs, testing the power transistor unit and testing the ignition coil (all checked out ok) I finally pulled the ECU.

Once I opened the case I was able to smell the same burnt anti-freeze smell, however I saw no physical damage to the board.

If you check the wire diagrams for these cars you can trace the ignition system back.

When the ignition is ON there is a constant power to the Power Transistor unit. When the PTU is fed signal (from the ECU) it will switch power to the Ignition Coil. The ignition coil will supply high voltage power to the spark plug.

If the PTU is OK and the Ignition Coil is OK then it is either with the computer or the sensors the computer use to engage the PTU.

From what I can tell it looks like the ECU uses the Camshaft Position Sensor (CMP) and the Crank Angle Sensor/Crankshaft Position Sensor (CAS/CPS).

The only way to test if it is the computer is to put a known-working ECU in your car or put yours in a known-working car (or send the ECU out for testing).

Also,

Turn the ignition ON but do not crank the car over.

This is when the CEL light should illuminate for 5 seconds and then turn off. At the same time the stock boost gauge should move to 0 PSI and then drop off.

Tell us if this happens (I know you stated the light does not come on, but does the boost gauge move to 0 psi?).

If this does not happen then it is either a fuse issue (which you have stated it is not) or it is a computer issue, as this sequence is the computer powering on.

 

[VETTE_50_TH]

RemmarGorp,

Neither of them happen. So wouldn't that mean that its a computer issue. Since the computer isn't coming on to power that CEL or to show there is no pressure at that moment?

Just my thought. You are ###### correct. My car is all torn apart though. As in the exhaust manifold off, intake, and upper intercooler pipe. I Don't think that makes a difference but just wondering. I don't have any friends who own this type of car but I could only get a new one.

Just wondering if there is anything i should try out before I go buy ANOTHER ECU for the car. I hate shelling out the money for something that shouldn't die in a year when i could be getting performance stuff instead. Sucks majorly!

James

 

[steve]

If the CEL doesn't turn on for 5 seconds and go off then the ECU isn't powering up. Nothing interesting is going to happen with the engine if the ECU isn't working. On turbo cars the boost gauge will go to zero and sit there until you try and start the car. Again, if that doesn't happen you have ECU issues.

The ECU needs power to work. That comes from two places, the room fuse than also maintains the radio's setting and the MPI fuse on the battery positive terminal. There is a relay the switches the MPI power to the ECU. To turn the ECU on the ignition fuse has to be good so that the ECU can see the switch turn on, that causes the ECU to pull the MPI relay coil low and activate the relay turning on the main power to the ECU.

You can measure the voltages and figure out where this process is failing. Look up the MPI diagram in your Factory Service Manual (or search my posts to find out where to download the 1G electrical section). Look to see if you have 12v at the input to the MPI relay and then check to see if you get 12v from the ignition switch to the ECU when the switch is un the run position. You see 12v at the output of the relay coil until the ignition is on and then if the ECU is good it will pull the coil low closing the relay contacts and putting 12v to the ECU main power pins.

Considering how common ECU failure is due to capacitor leakage, the is one of the first things to check when your car won't start.

Steve

Oh, and if you suspect that the ECU is acting up have it checked before replacing it. New ECUs from the dealer are $1200, used ECU in various usable conditions run between $100 to $400. repairing them when possible <$250.

 

[moco2448]

hi there sorry to jump in but im haven the same problem on my 90 dsm laser turbo bought newer ecu orignally had a 91 ecu in car just got a 90 ecu now car wont run ??? wondering when caps blow do they fry anything else? if so is that the problem were running into and ive been looking on these posts and a bunch of people are havin this problem right now no one is really fixin it one post said somethin about a fuse in the alternator??? couldnt see one myself but they were talkin about a diff year of dsm ....ps sorry for jumping in

 

[JusMX141]

ps sorry for jumping in

I don't think anyone in the conversation will be offended seeing as this thread is almost four years old.

 

[hypergenesis]

Check if you can push start the car it could be your starter/ starter solenoid? The same thing happened to mine randomly and the CEL wasn't on either

 

[Calan]

I don't think anyone in the conversation will be offended seeing as this thread is almost four years old.

Damn it, you beat me to it.

Wonder if James ever got his car started?

http://www.dsmtuners.com/forums/search.php

 

[dikdiamond]

hi there sorry to jump in but im haven the same problem on my 90 dsm laser turbo bought newer ecu orignally had a 91 ecu in car just got a 90 ecu now car wont run ??? wondering when caps blow do they fry anything else? if so is that the problem were running into and ive been looking on these posts and a bunch of people are havin this problem right now no one is really fixin it one post said somethin about a fuse in the alternator??? couldnt see one myself but they were talkin about a diff year of dsm ....ps sorry for jumping in

If your car originally had a '91 ecu that means that two wires in the ecu harness have been switched,and need switched back so that the '90 ecu works properly. I'm looking through the forums but I can't find which ones to change.

Edituh,here it is http://www.dsmtuners.com/forums/articles-electrical-wiring/302812-1991-1994-ecu-swap-into-1990-dsm-ignition-wiring.html

 

[VETTE_50_TH]

Damn it, you beat me to it.

Wonder if James ever got his car started?

http://www.dsmtuners.com/forums/search.php?searchid=9890628

. Yea i did. A long ass time ago. But i then cut it up and parted it. My new car is not starting because its completely torn apart. lulz

It was the ECU btw. I blew up two of them before i got smart and got one from Steve rebuilt.

 

[Calan]

. Yea i did. A long ass time ago

Well that's good, cause it would be some funny a$$ shlt if you came back in here and said you were still trying to figure it out.

 

[VETTE_50_TH]

As soon as i put in a friends ecu, it started right up.

That would have been funny.