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What makes an ECM RaNdOmLy not work?

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Old Jan 2, 2001 | 01:44 PM
  #1  
Yarnboy's Avatar
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From: Frederick, MD USA
What makes an ECM RaNdOmLy not work?

About every 45 starts my car will run like **** with horrific throttle response and code 34 and 36. Turn it off, let it sit for 25 seconds runs perfectly fine for the next 45 starts. I am 99 percent sure it is the ECM because a place said the grounds going into it are bad and I fixed the code 34 and 36. Random acts of crap **** me off. I am gonna go buy a reman ECM I guess..

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-Red '88 IROC 5 Speed 305 TPI w/3.08
-Dual Friction Centerforce Clutch
-Accel 300+ Racing Ignition
-Accel 300+ Pro Sleeve Plug Wires
-Accel U-Groove Plugs
-Flowmaster Force II 3 Chamber Cat Back Exhaust
-Hypertech Chip
-Hypertech Airfoil
-Removed, Then Re-installed (out of fear) MAF Screens
-Gutted Air Box
-Best E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 MPH 93.91
-Best 60' 2.17
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Old Jan 2, 2001 | 05:19 PM
  #2  
Damon's Avatar
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From: Philly, PA
Yeah, it could be an ECM. The ONE time I genuinely had an ECM go bad it did weird stuff for no explicable reason. Engine would run, guages wouldn't work. Guages would work, engine wouldn't run. Crazy.

My ECM did have latent codes that indicated an bad ECM (no check engine light, though). Replaced the ECM with a junkyard replacement that Hollander said would work, swapped in my original chip out of the old ECM and never had another problem.
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Old Jan 2, 2001 | 06:59 PM
  #3  
GMTech's Avatar
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From: Vereinigten Staaten
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Poor solder joints usually. The ECM warms up and the solder joints make poor connetions and weird things happen.

As for the ECM making the gauges act funny, not really. The gauges and the ECM don't share any of the same sensors, so you had something other than the ECM wrong.

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'87 Trans Am
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JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
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Old Jan 3, 2001 | 11:40 AM
  #4  
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From: Frederick, MD USA
Is there a way to re-solder the joints? Or is it not worth it..are there any preventive measures I can take to try and stop this from happening again? It's gonna be 15 every night..I keep my car super warm inside..that ECM isnt to far away from the ducting so Im sure it goes through a dramatic temperature change..thanks alot for your reply..

------------------
-Red '88 IROC 5 Speed 305 TPI w/3.08
-Dual Friction Centerforce Clutch
-Accel 300+ Racing Ignition
-Accel 300+ Pro Sleeve Plug Wires
-Accel U-Groove Plugs
-Flowmaster Force II 3 Chamber Cat Back Exhaust
-Hypertech Chip
-Hypertech Airfoil
-Removed, Then Re-installed (out of fear) MAF Screens
-Gutted Air Box
-Best E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 MPH 93.91
-Best 60' 2.17
Reply
Old Jan 3, 2001 | 05:13 PM
  #5  
GMTech's Avatar
Supreme Member
 
Joined: Jul 1999
Posts: 2,767
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From: Vereinigten Staaten
Car: Take
Engine: Your
Transmission: Pick
If you have ever taken an ECM apart and seen how many solder joints are on the PC Board, you would understand. Not to mention, trying to find a failed one, and then properly fix it. Just get a reman, and let somebody else worry about it.

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
-->14.97 @ 94.9 MPH<--

'97 Bonneville SSE
Reply
Old Jan 5, 2001 | 12:03 PM
  #6  
Yarnboy's Avatar
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From: Frederick, MD USA
They said they thought it was the ECM ground..where is that? I could attatch my commadore 64 to a of couple wires and get better luck..Ya cant go wrong with 64k of RAM!

------------------
-Red '88 IROC 5 Speed 305 TPI w/3.08
-Dual Friction Centerforce Clutch
-Accel 300+ Racing Ignition
-Accel 300+ Pro Sleeve Plug Wires
-Accel U-Groove Plugs
-Flowmaster Force II 3 Chamber Cat Back Exhaust
-Hypertech Chip
-Hypertech Airfoil
-Removed, Then Re-installed (out of fear) MAF Screens
-Gutted Air Box
-Best E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 MPH 93.91
-Best 60' 2.17
Reply
Old Jan 5, 2001 | 09:11 PM
  #7  
Damon's Avatar
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Joined: Sep 1999
Posts: 7,072
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From: Philly, PA
If you own an 88 Grand Am the ECM DOES run all the guages. The FBody of earlier years works a little different, I'm sure. Just tyring to give an example of the weirdness I expereinced. Sorry if it confused.

Lord help you if you are soldering things inside the ECM to try to solve this problem.
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Old Jan 5, 2001 | 09:21 PM
  #8  
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Yup.

Unless you're really lucky, or have a wave soldering machine and a robotic pick & place, forget about messing with all the surface mount components on the ECM mainboard. There are some ribbon cables and plated-through solder pads on some of the major components and terminals (like the edge connectors and injector output transistors) but most of the items are surface mount and smaller than a Ford driver's we-we thang....

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Vader
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[This message has been edited by Vader (edited January 05, 2001).]
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