bad DIS?

jdsgallops

Registered User
About a year and a half ago I was trying to merge onto the interstate when my 90sc just died. No attempt at a restart would work. Towed it home and let it sit while I dealt with my divorce. Over the last 6 months or so I have been chasing the problem. Shift light stayed on so in went a new cranki sensor. No luck. Found the harmonic balancer wobble and replaced with a SFI BHJ. No luck. Pulled the engine and much to my surprise found a 2 piece crank. After procuring an entire new motor and using the best parts between the two I finally have the car back together and am trying to start it. Starter turns over but no fire. I have verified fuel at the rail. Cam sensor was installed with #1 piston at TDC and shaft aligned with mark. My next step is to verify this along with testing for spark. Shift light goes off when cranking. With the DIS system firing 2 cylinders at a time I would expect to hear a cough once in a while though if timing was just off. Which leads me to believe I have no spark, which I will verify when I have time. If I do indeed have no spark would I start to look at the DIS module. I have a spare here, assumably good from the 2nd engine I purchased. All wiring has been double checked from engine reinstall and all is connected.
 
Cam sensor was installed with #1 piston at TDC and shaft aligned with mark.

It's supposed to be installed with #1 cylinder (compression stroke) 26 degrees after top dead center. If you unplug the sensor the computer will guess at the correct sequence (1 in 3 chance).

David
 
I would also check to make sure you have injector pulse. That is if you don't smell gas from the cranking of the engine.
 
Sure that the EEC ground next to the battery is fully connected?

Does the radiator fan come on when the key is turned to "On"?

Did you check the actual pressure at the fuel rail test port, before and during crank?
 
Sure that the EEC ground next to the battery is fully connected?

Does the radiator fan come on when the key is turned to "On"?

Did you check the actual pressure at the fuel rail test port, before and during crank?

X2.

That ground burned me for 2 days of trouble shooting and swapping known good parts on the last one I restorected from the dead. Had fuel at the rail, but no pressure, fuel pump was not cycling, fan on w/key, and no inj pulse.

Adam
 
Dave all the info I found stated to install at top dead center and then set to mark, assuming mark was made prior to disassembly. Since the mark on the shaft was there prior to my ownership I am assuming that is what the mark is for. With it set to the mark it is pointed in the correct direction. This is why I need to reverify.

As far as ground goes I am pretty sure that I have all of them reconnected. The one by the battery should not have been disconnected to get the engine out. As it stands now the battery is grounded to the drivers side motor mount and there is a grounding strap from the passenger motor mount to the frame rail under the coolant overflow tank. I am going to agree with you guys though as I do not smell fuel after cranking, I seem to have no spark, and my tweecer is not able to talk to the computer. All familiar as I needed to add another ground strap from the engine to firewall on my Mustang.

I should have added in my original post the ignition switch seems to be bad. Car will crank fine for 2 or 3 revolutions and then "kicks back". Using the remote starter on the solenoid the car turns over fine. Looks like I need to replace it and verify my grounds before I go any further. Thanks for the suggestions!
 
Smell of no fuel could mean injectors aren't firing. EEC controls injectors. Not being able to access the computer sounds like a computer or reader problem.

But just with those two it sounds as tho your EEC isn't working.
 
89 and 90 SC's dont have an EEC test connection, they are blackbox only (unless you have a Quarterhorse or some other similar chip). Here is the test procedure for the 89-90 SC DIS. http://mnharms.com/tutorials/disnostart/


I have a 90 cougar XR7. There is a port in the engine bay that is labeled "EEC test connector". You plug in the code reader there. You do the KOEO and KOER test thru there

Not being able to retrieve codes indicates that either 1) you have faulty wiring. 2) loss of power to the EEC. 3) bad EEC ground. 4) bad EEC.
 
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As it stands now the battery is grounded to the drivers side motor mount and there is a grounding strap from the passenger motor mount to the frame rail under the coolant overflow tank.

The negative battery cable (at least on all all the years I am familiar with) also has a small gauge wire (10 or 12) that connects to a ground lug on the radiator support. Is that installed? From there, it goes down, through a barrel connector, and then across the car and to the EEC. That is the critical ground connection for the EEC. I would trace that or get long multimeter leads and test continuity from the EEC harness connector to that barrel connector.
 
Dave all the info I found stated to install at top dead center and then set to mark, assuming mark was made prior to disassembly. Since the mark on the shaft was there prior to my ownership I am assuming that is what the mark is for. With it set to the mark it is pointed in the correct direction. This is why I need to reverify.

I'm not sure if you are talking about a mark on the sensor stalk or on the balancer. Doesn't matter because if you are setting it up to top dead center and then installing the stalk it's not going to work. Follow the instructions in this post for properly installing the cam sensor stalk.

http://www.sccoa.com/forums/showpost.php?p=365956&postcount=2

David
 
The negative battery cable (at least on all all the years I am familiar with) also has a small gauge wire (10 or 12) that connects to a ground lug on the radiator support. Is that installed? From there, it goes down, through a barrel connector, and then across the car and to the EEC. That is the critical ground connection for the EEC. I would trace that or get long multimeter leads and test continuity from the EEC harness connector to that barrel connector.

A quick look when I got home from work last night. The ground you are talking about has double wires coming out of it. One is the wire going across the engine bay towards the EEC. The other is missing. I have two ground leads unused on the battery cable. Sounds like I need to run a ground wire here. Simple fix hopefully.

David thanks for the link. Once the other issues are resolved I will address this issue as it has been my biggest concern in getting the car running again.
 
A quick look when I got home from work last night. The ground you are talking about has double wires coming out of it. One is the wire going across the engine bay towards the EEC. The other is missing. I have two ground leads unused on the battery cable. Sounds like I need to run a ground wire here. Simple fix hopefully.

David thanks for the link. Once the other issues are resolved I will address this issue as it has been my biggest concern in getting the car running again.

I think you will be pleasantly surprised once you add a ground there. :)

By the way, if the cam sensor is out of position, you can unplug it and run without it temporarily, though starting will probably take a few tries.
 
I've never seen an SC that didn't have an EEC/VIP Self-Test connector - for a 1990: engine bay, passenger side, back against the firewall where the fender turns down. Grey connector and pigtail.

See location 2-C, Figure 2, on the first page (218) in the Component Locator.

This image shows how to set up to manually check codes/count flashes instead of just plugging in a reader.

4hup96.gif
 
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Sorry to highjack this thread.
Here is a pic of the connectors i have, neither have the self test input
pigtail.
 

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Sorry to highjack this thread.
Here is a pic of the connectors i have, neither have the self test input
pigtail.

The EEC plug should have a cover just like the ARC cover, only colored black. The pigtail is supposed to tuck into that cover, but it is a separate wire. The self test input pigtail could have been accidentally severed somehow. I would take a hard look behind the wheel well.
 
Put a quick ground from the radiator support to the battery. I can hear the fuel pump cycling now but still no start. Turning over very hard. I have the trickle charger on the battery and it showed full charge. After 3 tries I checked the battery with the large charger it it was under 50%. The ignition switch seems to be robbing power and not letting it turn over well. Until it is replaced I am at a stand still it seems. I still can not get the Tweecer to communicate with the computer. I am hoping that I do not have the same issue I did on my mustang and because of the lack of ground for the computer, the computer became the ground blowing it out. Unfortunately the bolt that holds the wiring harness to the computer seems to be stripped out. Gotta love these cars. Every time you think you got it it throws another curve ball to keep you guessing.................
 
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