smoked computer second time what should I check?
- Thread starter jimilane
- Start date
I've been looking in the manuals.
It might be the start solenoid!!!
WHat do you guys think?
The resistance might be off in the thing.
AFter shutdown, if you try to immediatly try to restart, the starter is sluggish. If you wait for a few minutes, the car will start fine.
Right on the solenoid it say that if you don't use a FORD part, you could damage the computer...well I'm going to try that out and see what happens. I don't know that the FORD part is any better, but the warning is still the same no matter whick one you have.
Has anyone had this type of problem????\
Jim
It might be the start solenoid!!!
WHat do you guys think?
The resistance might be off in the thing.
AFter shutdown, if you try to immediatly try to restart, the starter is sluggish. If you wait for a few minutes, the car will start fine.
Right on the solenoid it say that if you don't use a FORD part, you could damage the computer...well I'm going to try that out and see what happens. I don't know that the FORD part is any better, but the warning is still the same no matter whick one you have.
Has anyone had this type of problem????\
Jim
TRWXXA
Member
Hey Jimmy!!
Still tryin' to figure out the computer problem? Wish I knew more about that kinda stuff.
Sounds like you have the right idea looking at the solenoid. get a Ford one, and check the one you have against it. Maybe the resistance is different.
See ya 'round "the hub".
Still tryin' to figure out the computer problem? Wish I knew more about that kinda stuff.
Sounds like you have the right idea looking at the solenoid. get a Ford one, and check the one you have against it. Maybe the resistance is different.
See ya 'round "the hub".
Possible bad ground...
Grounds are important to any electrical system, and especially to computers.
1.) The main power ground is from engine block to battery: it is the power ground for the starter & alternator.
2.) The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.
3.) The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
4.) All the sensors have a common separate ground. This includes the TPS, ACT, EGE, BAP, & VSS
5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. This is different and separate from the O2 sensor ground. It is in the fuel injector wiring harness and comes out under the throttle body. It gets connected to a manifold or head bolt.
6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself.
7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.
8.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally.
See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103#volt for help troubleshooting voltage drops across grounds
Grounds are important to any electrical system, and especially to computers.
1.) The main power ground is from engine block to battery: it is the power ground for the starter & alternator.
2.) The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.
3.) The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
4.) All the sensors have a common separate ground. This includes the TPS, ACT, EGE, BAP, & VSS
5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. This is different and separate from the O2 sensor ground. It is in the fuel injector wiring harness and comes out under the throttle body. It gets connected to a manifold or head bolt.
6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself.
7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.
8.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally.
See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103#volt for help troubleshooting voltage drops across grounds
I'll go throught the grounds again and see what I can find.
You seem to be going the ground route. Have you seen this a lot?
I just put an E303 cam in this weekend and had to disconnect/reconnect about 3/4 of the grounds you mentioned.
The ground to the block from the battery is good and the ground from the manifold to the firwall is good.
I checked out the computer remanufacturer's site. They say the major cause of smoking the computer is a bad relay or solenoid, 95% of the time. This of course will void the warranty if it is the relay/solenoid.
I think the start relay or it's ground may have something to do with it since the car starter turns slowly if you try to crank it right after you turn it off. This happens all the time. Even if you run the car the first time for just a few minutes. It's not enough time for anything to heat up from heat coming from the headers or engine...like the Chevy starter problems.
Maybe the starter...guess I'll get out to the shop.
Thanks,
Jim
You seem to be going the ground route. Have you seen this a lot?
I just put an E303 cam in this weekend and had to disconnect/reconnect about 3/4 of the grounds you mentioned.
The ground to the block from the battery is good and the ground from the manifold to the firwall is good.
I checked out the computer remanufacturer's site. They say the major cause of smoking the computer is a bad relay or solenoid, 95% of the time. This of course will void the warranty if it is the relay/solenoid.
I think the start relay or it's ground may have something to do with it since the car starter turns slowly if you try to crank it right after you turn it off. This happens all the time. Even if you run the car the first time for just a few minutes. It's not enough time for anything to heat up from heat coming from the headers or engine...like the Chevy starter problems.
Maybe the starter...guess I'll get out to the shop.
Thanks,
Jim
It seems the 1989-90 cars have a EEC Relay in between the start switch and the computer. I have a new one to put in along with a new start relay.
Then I'm going to start the car and see what happens.
If anyone can think of anything else, please let me know before I fry another computer...
By the way, the FORD folks and everyone else thinks that it's the start relay...
Jim
Then I'm going to start the car and see what happens.
If anyone can think of anything else, please let me know before I fry another computer...
By the way, the FORD folks and everyone else thinks that it's the start relay...
Jim
Well, I replaced the start relay/solenoid, the ECC Relay.
Also, the negative battery cable had been replaced and the pigtail had been crimpped in. I cut the wires back and made another connection. The old one didn't look bad though.
The car ran for 20 minutes with no problems except the idle, (I just installed an E303). The computer didn't heat up like it did last time. It ran a 92 degrees the whole time. No funny smell like last time either.(I was using an IR temp sensor).
I have an after market plate to go between the throttle body and the IAC valve to correct the idle problem...I knew it was coming....
I still haven't taken it out on the road yet.
Jim
Also, the negative battery cable had been replaced and the pigtail had been crimpped in. I cut the wires back and made another connection. The old one didn't look bad though.
The car ran for 20 minutes with no problems except the idle, (I just installed an E303). The computer didn't heat up like it did last time. It ran a 92 degrees the whole time. No funny smell like last time either.(I was using an IR temp sensor).
I have an after market plate to go between the throttle body and the IAC valve to correct the idle problem...I knew it was coming....
I still haven't taken it out on the road yet.
Jim
You cpu problem
Ok if your cpus are burning up than you have a a relay or silnoid thats shorted.You need to check all silonoids firs for over amping. check Your evp, diverter and air bypass silonoids and starter silonoids .hook up a dvom in line with the power wire to the relay/silonoids in question.Set your dvom to Miamps if you are drawing more than 750millamps you found a shorted relay/Silonoid. And that will burn up your cpu every time.So check that out and i bet you will find one shorted!!!!
Ok if your cpus are burning up than you have a a relay or silnoid thats shorted.You need to check all silonoids firs for over amping. check Your evp, diverter and air bypass silonoids and starter silonoids .hook up a dvom in line with the power wire to the relay/silonoids in question.Set your dvom to Miamps if you are drawing more than 750millamps you found a shorted relay/Silonoid. And that will burn up your cpu every time.So check that out and i bet you will find one shorted!!!!
I'm going to do some more checking before I take it on the road.
I checked the voltage in all the main power lines, under the hood and under the dash.
I checked for not less than 20 Ohms, not 750mamps. Not sure how that converts. I got the 20 Ohm from the computer manufacturer by the way.
So far I have ran the car for 20 minutes,(in the driveway), and then for another 30(in the driveway). So far the computer isn't heating up any and no smell is coming from the computer. I might take it out of the driveway one day.
Anyway, I have the car idling fairly well. Have to work out the PCV system. I relocated the PCV to the valve cover, with a different valve cover. The PCV in the intake manifold was sucking up too much oil before. I just thought I would try something different.
Jim
I checked the voltage in all the main power lines, under the hood and under the dash.
I checked for not less than 20 Ohms, not 750mamps. Not sure how that converts. I got the 20 Ohm from the computer manufacturer by the way.
So far I have ran the car for 20 minutes,(in the driveway), and then for another 30(in the driveway). So far the computer isn't heating up any and no smell is coming from the computer. I might take it out of the driveway one day.
Anyway, I have the car idling fairly well. Have to work out the PCV system. I relocated the PCV to the valve cover, with a different valve cover. The PCV in the intake manifold was sucking up too much oil before. I just thought I would try something different.
Jim
I took it out on the road.
The E303 does really well!!!
I drove around playing for about an hour and the computer never smoked or changed temperature or started smelling.
The spacer for the IAC worked as advertised with no adjustments needed. Just bolted it on and everything is good.
The only problem now is the crankcase isn't getting ventilated very well. There is no suction at the small tube at the oil filler like there is supposed to be. Probably a vaume leak somewhere.
The cam lowered the vacume from 17 to 15 by the way.
Jim
The E303 does really well!!!
I drove around playing for about an hour and the computer never smoked or changed temperature or started smelling.
The spacer for the IAC worked as advertised with no adjustments needed. Just bolted it on and everything is good.
The only problem now is the crankcase isn't getting ventilated very well. There is no suction at the small tube at the oil filler like there is supposed to be. Probably a vaume leak somewhere.
The cam lowered the vacume from 17 to 15 by the way.
Jim
With the E-303 cam if you are running 1.7 rockers than you add more lift to your valves And about 2-3 more degs to your cam! and that will cause less vac!My 89 with E-303 gets about 15 in hg of vac with 1.7 rockers on it and more lope! lust put a check valve on your brake booster and it will work great!
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