Car won't start, turns over. No changes & was running fine.

[eclipsh]

I'm in the middle of moving and my car will not start. I pulled the plugs and grounded the edge to the valve cover and I didn't see spark on any of the four. I am getting voltage at the CAS and the coil pack. Nothing under the hood was touched. I did a JDM swap earlier this summer and did not know I needed to switch over the CAS. I am wondering if that may be playing into this, though I am not sure why it would have shown up now. The JDM was sold to me as a 90 GVR4 but had a different throttle body sensor cluster and coil/transistor pack so I suspect it was a 91 model. My 90 coil pack and transistor are on the car along with the 90 T/B.

The spark plugs appear to be in good condition and I can't see all four failing at once. I'm not sure where to start at now for fixing the problem. Any help is greatly appreciated and if there is anyone in the Durango, CO area I could really use your help. Thanks!!!

Also, my old engine is long gone so I do not have access to my old CAS or anything else off of it.

 

[eclipsh]

Here's the latest and greatest:

I went ahead and threw in the new coil pack I had laying around along with new plugs and wires. I was checking for spark and found that I am getting very weak and intermitent spark still. The timing light shows really random spark going to #4. Most of the time I couldn't even see a spark with the gap tester I'm using. I was jumped to another car and seeing 13v through the system. I don't know what else could be causing this. The computer is essentially in new condition, the CAS is used but is sending a signal so far as I can tell. The coil pack is new, wires are new, plugs are new and the power transistor tested good as far as I can tell. What the hell else is there? Could the CAS and transistor be bad after all and I just don't know it? I don't know what else is left besides maybe a bad wire in my harness...

 

[eclipsh]

I also checked the ignition wire (black & white) at the ignition and at the plug for the coil. I'm getting full voltage at both ends. I ran extra ground wires from the coil to the back of the head and from there to the negative pole of the battery. Now it won't start up at all, even first thing in the morning.

 

[steve]

Perhaps I missed it but what is the compression on that engine currently?
Are you now getting a strong spark at all the cylinders?
Are you getting fuel?

Get the logger working and check all the sensors. A bad ECT sensor can cause the car not to start

Steve

 

[eclipsh]

Perhaps I missed it but what is the compression on that engine currently?
Are you now getting a strong spark at all the cylinders?
Are you getting fuel?

Get the logger working and check all the sensors. A bad ECT sensor can cause the car not to start

Steve

I haven't checked the compression but I just dropped a JDM in a few months ago. I'll go test it anyhow. I am getting weak spark at all cylinders. I can smell fuel and all four plugs were wet when I pulled them after cranking so I should be good on fuel. When I hook the plug wires up to one of those gap testers (the screw in ones that clip to a ground and have a little black plastic box behind the screw so you can see the spark) I usually can't see any spark. A few times I saw a bright yellow spark but most of the time there was only a very thin blue line and a crackling sound.

My logger is not showing any error codes. I can't get very many readings since the car won't start and I bought it after the car died. I tested all the relays it could test and all of them clicked over. I don't see any relays in the ignition system to replace. Is there one that I'm not seeing and could replace?

 

[steve]

You should be able to read the Intake Air temp, the Barometric pressure, the Engine coolant temp and make sure that they have reasonable values. The IAT and ECT should be about the outside temp and close to each other until the car starts.

You should see the engine RPMs during cranking and get a reading from the MAF as well as an injector pulse width.

Spark depends on the engine having a good ground, a good set of coils, power transistor module and CAS. When testing the CAS the two outputs are pulled up to 5v by the ECU. If you take it off and turn it by hand you see the voltage on the crank and cam outputs switch from 5v to ground and back to 5v as you turn it.

The stuff in the engine bay gets power from either the MPI relay or the ignition switch and the two fuses that go with. Since the ECU powers up and fuel pump runs it sounds like both of them are working.

Check the compression, get a new set of plugs, make sure the ECT isn't reading something like -32F and making the car too rich to start and let us know what you find.

Steve

 

[eclipsh]

You should be able to read the Intake Air temp, the Barometric pressure, the Engine coolant temp and make sure that they have reasonable values. The IAT and ECT should be about the outside temp and close to each other until the car starts.

You should see the engine RPMs during cranking and get a reading from the MAF as well as an injector pulse width.

Spark depends on the engine having a good ground, a good set of coils, power transistor module and CAS. When testing the CAS the two outputs are pulled up to 5v by the ECU. If you take it off and turn it by hand you see the voltage on the crank and cam outputs switch from 5v to ground and back to 5v as you turn it.

The stuff in the engine bay gets power from either the MPI relay or the ignition switch and the two fuses that go with. Since the ECU powers up and fuel pump runs it sounds like both of them are working.

Check the compression, get a new set of plugs, make sure the ECT isn't reading something like -32F and making the car too rich to start and let us know what you find.

Steve

Intake air temp, coolant temp, barometric pressure etc all look good. The O2 is showing .04v w/o cranking. Unfortunately I have the power feed for my pocketlogger coming from the lighter so it doesn't work while cranking. Where should I hook it up so it works all the time? I have brand new plugs in it already along with new wires. Please clarify MPI as I am an ignorant newb Could a relay just be weak and not be letting enough current through to get good spark?

 

[steve]

Could a relay just be weak and not be letting enough current through to get good spark?

Nope, the coils and PTM get power from the ignition switch. The PTM pulls one side of a coil primary to ground to make current flow to charge up the electric field and when it switches off the field collapses creating a current in the secondary which causes the plugs to spark. Since we use a wasted spark setup, that means the spark jumps from ground to the plug on one plug and from the plug to ground on the other. A bad connection on either plug will effect both.

On a 1G the MPI relay is the small gold box bolted to the passenger side of the center console in front of the ECU. It supplies power to the ECU and all the solenoids as well as switches on the fuel pump.

Steve

 

[eclipsh]

So then, if the used PTM I bought was bad and I just didn't test it right would I get weak and irregular spark?

 

[steve]

So then, if the used PTM I bought was bad and I just didn't test it right would I get weak and irregular spark?

If it's bad or it doesn't have a good ground it can cause a weak spark.

Steve

 

[eclipsh]

The ground on it should be good. I tested it by checking the voltage of the ignition and using the back of it as the ground.

 

[LockeXSG]

Nope, the coils and PTM get power from the ignition switch. The PTM pulls one side of a coil primary to ground to make current flow to charge up the electric field and when it switches off the field collapses creating a current in the secondary which causes the plugs to spark. Since we use a wasted spark setup, that means the spark jumps from ground to the plug on one plug and from the plug to ground on the other. A bad connection on either plug will effect both.

On a 1G the MPI relay is the small gold box bolted to the passenger side of the center console in front of the ECU. It supplies power to the ECU and all the solenoids as well as switches on the fuel pump.

Steve

Would that little relay cause the car not to get spark or fuel coming out of the injectors. I have changed out coil, transitor pack, cas, and ecu. I check the original stuff and the only thing that was bad was the ecu. Even with the new ecu its not cranking.

Also if that small gold box doesn't have a ground that would cause the ecu not to get power.

 

[steve]

A bad MPI relay will keep the ECU from running and that will cause no spark or injectors.

The MPI relay has several pins that are either grounded or get grounded so which pins do you mean?


Mr Locke, Please fix your profile ASAP.

Steve

 

[LockeXSG]

Well you actually anwered my question with say that the pins are grounded through the harness.

I am not sure what you are talking about with my profile but I took a quess and changed things soo..... WTF

 

[steve]

I am not sure what you are talking about with my profile

Update your vehicle please.

Steve

 

[jasoncitrano]

What's the update on this? When you crank it are you still getting no engine RPM?



P.S. What's up steve? I'm the guy you got the lawyer for remember!

 

[LockeXSG]

Well I am still not getting any spark and my fuel injectors are not kicken on either. So... I am in the process of checking my wiring harness for grounds and shorts. This will probably take me forever but... I hope to figure something out soon. I would like to work on something other than getting the car to just run!

Updated!!

 

[steve]

Well I am still not getting any spark and my fuel injectors are not kicken on either.

OK, check to see if the CEL light comes on for a few seconds when you first turn the ignition on and that the factory boost gauge goes to zero.

If it doesn't check the MPI fuse on the positive battery terminal.

You need to start your own thread, this one is eclipsh's and what your doing is called thread hijacking and considered rude.

Steve

 

[eclipsh]

Well, I got a brand-spanking new ICM in and tested it side-by-side with the other to ICM's I've got. They all test identical. So I'll be returning the new ICM and now I REALLY don't know what to check out next. I think I'll be towing the car to a mechanic unless anyone has a few more ideas.

My last ditch option is testing all the wires at the ICM but my factory manual CD doesn't have the wiring for the 90 5 wire, only 91+ 7 wire. Does anyone have a wiring diagram for it and know what sort of voltages etc I should be getting where?

 

[steve]

Well, I got a brand-spanking new ICM in and tested it side-by-side with the other to ICM's I've got. They all test identical. So I'll be returning the new ICM and now I REALLY don't know what to check out next.

My last ditch option is testing all the wires at the ICM but my factory manual CD doesn't have the wiring for the 90 5 wire, only 91+ 7 wire. Does anyone have a wiring diagram for it and know what sort of voltages etc I should be getting where?

ICM? You talking about the Power Transistor? The difference between the two is the later PTM has the output for the tach rather than the one on the coil pack in '90's.

The only '90 diagrams I've found are the one on the Mark Hamilton site other than the basic stuff in the 1G DSM tech manual on the Manual CD.
http://www.ecanfix.com/~mdhamilton/index.shtml

Steve

 

[eclipsh]

I went and checked out a few more things today. The boost gague comes up to just the bottom of the fat line below 0 and the oil pressure gague comes up to max, which I never paid attention to before so I don't know if that is normal. The ISC step is reading 120 with the ignition on. I would have thought it'd read 0... I also double checked and the fuel pump relay does click when tested. All the other relays are clicking too. I can hear spark and if I stare really close I can sort of see a thin blue line, but nothing like I'd expect to see compared to spark plugs I've seen light up. I'm towing the car to a mechanic tonight after work but if I can get some last ideas I might save a few $ I don't have. Any Wisemen looking at this, including Steve (thanks for all the help, btw,) if you can send a few others this way I'd be extremely grateful.

Steve: I was talking about the PTM. All three I had (one brand new, two used) tested identical (good.) Unfortunately the wiring diagrams on the website don't show any of the ignition system parts I'm checking. Neither does the tech manual CD. Guess I'm SOL on that one.

 

[eclipsh]

So... I got word back from my mechanic. I was dead wrong about the spark. It was fuel after all. Turns out the idiot who installed my walbro pump managed to pinch the power wire for it with the cover plate. It finally wore enough that it was grounding out. Guess I'm lucky the car didn't explode. He's fixing the wire and checking to make sure the extra draw didn't effect the relay or pump itself. I should have it back in a day or two. Thanks to everyone for the help and sorry i'm such a goof.