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I have a 1990 mustang with a 5.0 engine. At about 35 MPH ...

Sent to Car Experts April 22 2006 at 1:42 PM
   

I have a 1990 mustang with a 5.0 engine. At about 35 MPH cylinders 5 & 8 misfire. We have replaced the following parts, distributor,computer, ignition wires, plugs,,distributor cap,rotor, coil . We have also cleaned all fuel injectors.

 

Optional Information:
1990 Ford Mustang 5.0 V8

Already Tried:
replaced coil,distributor,computer,tfi module, distributor cap, rotor,ignition wires, plugs

Customer (name blocked for privacy)
Status:  Closed   Value: $15
Answer
April 22 2006 at 1:49 PM (6 minutes and 49 seconds later)
         
REPLIEDCheck Mark

Welcome to JA,

You need to do a wet and dry compression test on those cylinders to see if you have a problem in the valves or pistons.

It could be that at that rpm and up there is enough leakage to cause a misfire.

Hope this helps, an accept would be appreciated.



If more information is needed, please ask me.

Hope this helps, an accept would be appreciated.
Firsthogman
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Firsthogman -- Auto Service Technician -- 96% Positive Feedback on 300 Car Accepts
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Reply
April 22 2006 at 1:54 PM (4 minutes and 53 seconds later)
         
Reply to Firsthogman's Post: We have already done a compression test on all cyliders, and by the way we have also chaged the TFI module

Martin
Customer (name blocked for privacy)
Answer
April 22 2006 at 4:20 PM (2 hours and 26 minutes and 11 seconds later)
         
ACCEPTEDCheck Mark

If the compression was equal on all cylinders, it has to be something with the fuel or the ignition. Since you cleaned the injectors they should be okay. I would still check the two that are misfiring with a noid light. There could be something wrong in the wiring. I would presume the module is okay since you have changed it. The timing components that would cause this are the cam shaft interup magnet, camshaft sensor, crank shaft sensor and timing chain set ( I don't believe the chain set would affect just two cylinders). I can't think of anything else that would affect two specific cylinders, unless the injectors were just bad on those and you put them back in the same positions.

Hope this helps, an accept would be appreciated.



If more information is needed, please ask me.

Hope this helps, an accept would be appreciated.
Firsthogman
Love them Harley's
Picture
Firsthogman -- Auto Service Technician -- 96% Positive Feedback on 300 Car Accepts
40 years as a mechanic on all type equipment.
Reply
November 13 2007 at 3:02 AM (569 days and 10 hours later)
         
After all that we checked and replaced on the engine, it turned out to be sludge in the gas tank.At highway speeds where there was no sloshing in the tank the car ran fine, when the car was in stop and go traffic that is when the problem developed. When we finally changed the tank & of course the filter, the black gook that was in the bottom of the taken was unbelievable. Now that the new tank has been in (over 9 Months) I have had no problem
Customer (name blocked for privacy)
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