1984 Computer Issue
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Instructor
Joined: Jul 2009
Posts: 128
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From: Haslet Texas
1984 Computer Issue
What is the best way to get to the ECM under the dashboard? I've already taken off the front cover, but there's a metal plate behind it. My TPS is acting up and my manual said I might have an open circuit or short to ground in circuit 417 or ECM Connector pin 5 might be bad but I cant test it if I can't get to it. I.m getting 5.06 volts when I jump B and C so I know I'm getting enough power.
Race Director
Joined: Dec 2003
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From: Fremont Ca
2022 C4 of the Year Finalist - Modified
The ECM is on the left,remove the hush panel,take out the seat,aeat track and look up.The ECM is mounted straight up.If the TPS is acting up it should store a trouble code.
Race Director
Joined: Dec 2000
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From: El Paso Texas
Pulling the dash pad out is a 5 minute affair. I went at it from the top. The ECM is under the passenger side just behind the bread box. With the dash pad removed, you have plenty of access.
Why would you remove the seat? That's a ton of unnecessary work.
Why would you remove the seat? That's a ton of unnecessary work.
Thread Starter
Instructor
Joined: Jul 2009
Posts: 128
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From: Haslet Texas
Well, I didn't actually remove the seat the last time, I just crawled in upside down. What all do I need to remove to get behind the dash? It looks to be all in one piece. There's a couple of little holes about six inches wide, but it's pretty tight in there. Now that I've got internet at my house, I'll try to post some pics to show what I'm talking about later today when I get off work.
Drifting
Joined: Jan 2008
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From: New Madison Ohio
..with the dog once again..
Thread Starter
Instructor
Joined: Jul 2009
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From: Haslet Texas
Well, I tested the ECM and it was fine, so I went ahead and replaced the TPS switch instead and it runs a little better, but it could still use a little tweeking I suppose. The throttle has a little too much slack in it for my taste. Any ideas on how to take out the slack? The idle adjuster screw is at its lowest point point already and I think it needs to be replaced since it has no play left in it.
Burning Brakes
Joined: Jan 2008
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From: Superior WI
Well, I tested the ECM and it was fine, so I went ahead and replaced the TPS switch instead and it runs a little better, but it could still use a little tweeking I suppose. The throttle has a little too much slack in it for my taste. Any ideas on how to take out the slack? The idle adjuster screw is at its lowest point point already and I think it needs to be replaced since it has no play left in it.
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Race Director
Joined: Dec 2000
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From: El Paso Texas
There is no "idle adjustment" screw. The center screw, as Kangi mentioned, is used to balance the throttle bodies. If you have slack in the throttle, either the cable has stretched or the throttle body bushings are worn.
BTW....balancing your throttle bodies can solve a lot of issues on the Crossfire. It should be done every few years.
BTW....balancing your throttle bodies can solve a lot of issues on the Crossfire. It should be done every few years.
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Instructor
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From: Haslet Texas
The injectors look to be balanced because they react the same with the same amount of fuel at the same time, but I'll keep that in mind. I think I may have to replace the throttle cable. There don't look to be any way to take out the slack that's in it unless someone has some ideas.
Last edited by johnnyboyC4; Apr 9, 2010 at 11:10 AM.
Race Director
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From: El Paso Texas
You aren't balancing the injectors.....what you're doing when you balance the throttle bodies is ensuring that each butterfly is flowing the same amount of air into the engine.
Remember that each TBI supplies fuel and air to one bank of the engine. If the TBI's aren't synchronized, one bank of the engine is getting more fuel and air than the other at a given throttle angle. This can cause rough idle, poor fuel economy, loss of power, and a generally bad running engine.
Balancing the TBI's will solve a host of issues.
Remember that each TBI supplies fuel and air to one bank of the engine. If the TBI's aren't synchronized, one bank of the engine is getting more fuel and air than the other at a given throttle angle. This can cause rough idle, poor fuel economy, loss of power, and a generally bad running engine.
Balancing the TBI's will solve a host of issues.
Drifting
Joined: Jan 2007
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From: Supreme Soviet Peace-Loving Pipple's Kollektive of Seattle Wa
My FSM is loaned out right now, so I have to ask, is there a procedure in the FSM for balancing the TBI's? Or, is there a simplified way of doing this and with what tools(vacuum guage,etc)?
Race Director
Joined: Dec 2000
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From: El Paso Texas
It's in your FSM, and it's even in the cheapo Haynes manual. You will need a Water (slack tube) manometer. A vacuum gauge isn't sensitive enough. Water manometers aren't used much anymore, so they can be tough to find at a local tool store....but you can find them on a certain online auction site..
Dwyer Slack Tube Manometer
As you can see, not much to it. You could even make one out of plastic tubing, a piece of wood with a ruler on it, and some food coloring.
It's been a while since I've done it, but I believe you set each TBI to 6" of water at idle. The manual will give you the exact number.
The TBI's are sealed at the factory, so you have to "break" the seal.....ie pop out the cap to get to the adjustment screw on the TBI. Again, procedure is spelled out in the manual....it involves drilling so READ IT CAREFULLY before doing anything. You also have to grind the collar off the middle adjustment screw so it can adjusted. GM didn't want backyard grease monkeys doing this back in the day, so they sealed up everything.
It will make a world of difference in how the CFI runs if the TBI's were out of sync.
Dwyer Slack Tube Manometer
As you can see, not much to it. You could even make one out of plastic tubing, a piece of wood with a ruler on it, and some food coloring.
It's been a while since I've done it, but I believe you set each TBI to 6" of water at idle. The manual will give you the exact number.
The TBI's are sealed at the factory, so you have to "break" the seal.....ie pop out the cap to get to the adjustment screw on the TBI. Again, procedure is spelled out in the manual....it involves drilling so READ IT CAREFULLY before doing anything. You also have to grind the collar off the middle adjustment screw so it can adjusted. GM didn't want backyard grease monkeys doing this back in the day, so they sealed up everything.
It will make a world of difference in how the CFI runs if the TBI's were out of sync.
Drifting
Joined: Jan 2007
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From: Supreme Soviet Peace-Loving Pipple's Kollektive of Seattle Wa
Thanks Friz, for the info (as usual).. gonna' stick this on the project calendar. Nothing like a new venture to test one's panic-response after the point-of-no-return passes....
Thread Starter
Instructor
Joined: Jul 2009
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From: Haslet Texas
Well, I checked the TBI's and they are sycronized. I still think there's something going on with my throttle cable. I will try to take out the slack in it tomorrow. BTW, the book is very informative on the process of syncronization. Not bad for $20 on eBay.
Thread Starter
Instructor
Joined: Jul 2009
Posts: 128
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From: Haslet Texas
I think the problem might lie with the adjustment screw BEHIND the TPS. The fuel has immediate response when I play with the tang on the TPS, but takes time to open the butterflies on the TBI's when I pull up on the throttle bar. I may need to adjust the adjustment switch. It looks like it's sitting too far back and that's where I'm getting the lack of response from the injectors.
Last edited by johnnyboyC4; Apr 11, 2010 at 11:03 PM.
Le Mans Master
Joined: May 2006
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From: Irvine Ca
Two ways,
1) Load them to a flicker account and then copy and paste the URL address to this site
2) load them up to your personal account on here under User control panel...then again copy and paste the URL to the thread you want.
1) Load them to a flicker account and then copy and paste the URL address to this site
2) load them up to your personal account on here under User control panel...then again copy and paste the URL to the thread you want.
