Hesitation and miss

Tiny
THE.GREEN.MACHINE
  • MEMBER
  • 1995 FORD F-150
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 240,000 MILES
Symptoms;
. 1. Slight miss at idle.
. 2. Will not accelerate unless throttle is darn near floored, and maybe one out of ten times it will seem to function as it should.
. 3. CEL comes on but only intermittently, never at idle.
. 4. Exhaust seems to blow out much harder than my 92 with the 300 and my friends 2006 with the 5.4L.
. 5. Catalytic converter seems too hot to me.

checked;
. 1. Plugs (all good and getting spark).
. 2. All vac lines look good, no hissing.
. 3. Timing is perfect.
. 4. Spray carburetor cleaner all around vac lines, EGR, intake and even the plugs with no change in running.
. 5. Fuel pressure (34 key on and about 37 psi running).
. 6. Compression in tolerance of Haynes manual, I forget what they all were but we are withing 10% of each other.
. * Tried to pull codes, by the way, will not show codes at idle and I think the diagnostic port for the obd 1 is messed up, have tried with and without obd 1 scan tool.

The following are all things that have been replaced (for give my part swapping, as I could not pull codes it was kind of a best guess scenario).

Replaced:
. 1. EGR.
. 2. Fuel pump regulator (old one was bent where vac. Hooked up anyways).
. 3. TPS.
. 4. IAC.
. 5. Fuel filter.
. 6. Throttle body gasket.
. 7. Air filter.
. 8. MAF.
. 9. Battery (kind of unrelated as old one was shot anyways).

The next things on my list to try (unless you fine folks here can help) is to try a new coil and I may hollow out the catalytic converter since it seems to me like it gets much hotter than it should. After this I am at a complete loss (more than before). I have tried not to just throw parts at it, but nothing is seeming to workout right. It is a truck I bought from a friend and he is at a loss too. Any help would be greatly appreciated.
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Monday, February 13th, 2017 AT 10:18 AM

9 Replies

Tiny
HMAC300
  • EXPERT
Put a vacuum gauge on intake if you can and take a reading at idle if 15" or below it may be a plugged exhaust. There is a way a mechanic can test this through O2 sensor for back pressure as well.
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Monday, February 13th, 2017 AT 12:03 PM
Tiny
THE.GREEN.MACHINE
  • MEMBER
Thank you, I will try to get a vacuum gauge and test it. Would this cause an intermittent CEL? The truck had a glass-pack also that was welded on, but I cut the pipe right after the catalytic converter until I can solve this, so. The glass-pack is not in question anymore. Also, if I may be more of a bother, can you think of anything besides a catalytic converter that can cause my problems?
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Monday, February 13th, 2017 AT 12:54 PM
Tiny
HMAC300
  • EXPERT
Not unless I scanned for codes. Make sure all your engine grommets are okay with no air leaks. Have you disconnected exhaust just to see if it makes a difference? That would tell you quick if converter was bad.
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Monday, February 13th, 2017 AT 1:15 PM
Tiny
THE.GREEN.MACHINE
  • MEMBER
It has got quite a bit of dirt caked on the exhaust so I have not yet and I did not get a chance to work on it today either like I thought I would. I checked all grommets and seems to be fine, and I sprayed carburetor cleaner around intake, all vacuum hoses and plugs with no luck. Just trying to make sure I know everything I can check before I go back and work on it. It is two hours from my home. Do you know any tricks to using the Innova obd1 scanner? It works on my 1992 F-150, but I plug it in to this truck and nothing. Tried following the instructions in the scanner book to jump ground to initiate self test and still nothing. I have around 2.7 vdc at the two bottom center pins of the eec test port and ground at the individual wire.
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Monday, February 13th, 2017 AT 5:00 PM
Tiny
HMAC300
  • EXPERT
Your scanner will not work on your truck you have an OBD2 system not OBD1 so they will not read. The only way to get codes from yours is to use an obd2 scanner auto parts does for free or you can buy them fairly cheap, but they only read engine/transmission codes.
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Tuesday, February 14th, 2017 AT 5:37 AM
Tiny
THE.GREEN.MACHINE
  • MEMBER
Where would the obd 2 port be at? It still has obd 1 EEC IV port under hood.
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Tuesday, February 14th, 2017 AT 6:32 AM
Tiny
HMAC300
  • EXPERT
Jump with a wire and key on for check engine light to flash get back with codes yours is still under hood. See pictures.
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Tuesday, February 14th, 2017 AT 7:11 AM
Tiny
THE.GREEN.MACHINE
  • MEMBER
Yeah, that is obd 1 and I tried that.
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Tuesday, February 14th, 2017 AT 7:23 AM
Tiny
KEN
  • ADMIN
Did you get any codes? here is a guide to help also.

https://www.2carpros.com/articles/ford-lincoln-mercury-obd1-1995-and-earlier-diagnostic-trouble-code-definition-and-retrieval

Please let us know happens so it will help others.

Best, Ken
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Friday, February 17th, 2017 AT 3:28 PM

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