HELP! Before I go nuts!
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Junior User
Joined: Dec 2004
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HELP! Before I go nuts!
Ok, here's my situation-
I just took off the throttle body and upper intake plenum so I could change the passenger side valve cover gasket on my '88 351 EB Bronco. Anyway, now that everything is back together, the truck runs like crap. I have checked EVERYTHING. The truck acts like its missing out, but it has brand new plugs, cap, wires and rotor and O2 sensor.
Anyway, I took off the IAC and cleaned it out, seems to be doing its job because when I unhook it the truck runs TERRIBLE and dies. Also cleaned the TPS. So, I am wondering if I messed something up on the TPS when I soaked it in carb cleaner and took it off the throttle body. I have taken everything back apart (intake, TB, ect..) three times and put back together, and it still runs just the same. No, there are no vacuum leaks or anything of that nature. So is it possible the TPS could make the engine shake and stumble as if its missing out? I have checked all of the obvious numerous times and nothing is making the situation better. The engine idles where it normally did, but just very roughly. Someone told me the TPS could cause this since apparently it needs to be calibrated very precisely? How do I do this with the TERRIBLE location of the TPS on the bottom of the throttle body?
HELP before I go nuts! Thanks guys!
I just took off the throttle body and upper intake plenum so I could change the passenger side valve cover gasket on my '88 351 EB Bronco. Anyway, now that everything is back together, the truck runs like crap. I have checked EVERYTHING. The truck acts like its missing out, but it has brand new plugs, cap, wires and rotor and O2 sensor.
Anyway, I took off the IAC and cleaned it out, seems to be doing its job because when I unhook it the truck runs TERRIBLE and dies. Also cleaned the TPS. So, I am wondering if I messed something up on the TPS when I soaked it in carb cleaner and took it off the throttle body. I have taken everything back apart (intake, TB, ect..) three times and put back together, and it still runs just the same. No, there are no vacuum leaks or anything of that nature. So is it possible the TPS could make the engine shake and stumble as if its missing out? I have checked all of the obvious numerous times and nothing is making the situation better. The engine idles where it normally did, but just very roughly. Someone told me the TPS could cause this since apparently it needs to be calibrated very precisely? How do I do this with the TERRIBLE location of the TPS on the bottom of the throttle body?
HELP before I go nuts! Thanks guys!
Senior User
Joined: Apr 2004
Posts: 443
Likes: 1
From: Central Va.
Soak throttle body--yes- An electrical part like a TPS- no way!!!!I would replace TPS and I would take a very good look at the firing order(And #1 on cap IS #1 wire to #1 cylinder)- sounds like some plug wires are crossed.Vac. leaks cause a high idle concern. I would want to clear codes and run engine and see if you have a 63 code for TPS IF wires are not crossed- Hope this helps!! (note-pass side bank 1st cylinder is 1,next are2,3,4----Drivers side 1st cylinder is 5, next6,7,8)
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
I'll third the TPS concerns.
Also double check that the ground strap from the firewall (near the A/C bulkhead) to the upper intake support bracket got replaced when you reinstalled everything. Its the ground for the TPS and the EVP sensor. Without the ground neither of the two will function well if at all.
Also double check that the ground strap from the firewall (near the A/C bulkhead) to the upper intake support bracket got replaced when you reinstalled everything. Its the ground for the TPS and the EVP sensor. Without the ground neither of the two will function well if at all.
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Junior User
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Thanks guys. I'll just buy a new TPS because mine was on its way out anyway. (The idle fluctuated badly and I got a code for the TPS when I put the diagnostic scanner on the truck). Is there any special procedure I need to know to install and "calibrate" the new TPS? Also, how do you clear the codes?
Last edited by 76F250HighBoy; Apr 17, 2005 at 10:27 AM.
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Ok, I changed the TPS and it runs just the same. I have jiggled all the wires to see if there was a bad connection anywhere. I have checked EVERYTHING. I pulled the codes a long time ago (when it ran fine) and it gave me the following:
1. Thermactor air pump not working
2. TPS not working correctly
3. EGR valve not opening
It ran fine though, and I just pulled the codes today and I got something about a clogged fuel filter or line (Fuel filter was clogged the other day, but engine ran fine after I changed it), EGR valve not opening again, and it even said the TPS was still bad even after I just replaced it. I disconnected the battery for 10 mins to clear the computer and then reconnected and it still runs just the crappy same. Any other hints?
1. Thermactor air pump not working
2. TPS not working correctly
3. EGR valve not opening
It ran fine though, and I just pulled the codes today and I got something about a clogged fuel filter or line (Fuel filter was clogged the other day, but engine ran fine after I changed it), EGR valve not opening again, and it even said the TPS was still bad even after I just replaced it. I disconnected the battery for 10 mins to clear the computer and then reconnected and it still runs just the crappy same. Any other hints?
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
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Lead Driver
Joined: Jul 2003
Posts: 7,406
Likes: 52
From: Wheatland, Mo
Double check the firing order. Make sure your wires are all going from the right plug to the right port on the distrb cap.
If you do a search in this forum for "Firing Order" you will find a thread that has pics of the hookups.
If you do a search in this forum for "Firing Order" you will find a thread that has pics of the hookups.
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Senior User
Joined: Apr 2004
Posts: 443
Likes: 1
From: Central Va.
Please give us the codes read - not what you think they meant-example- code for no egr flow may not mean egr valve is bad- passages are probably stopped up etc.I am still leaning toward crossed plug wires-see 7&8 alot!!
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