Hi all,

I'm not sure were to go from here. I have replaced pretty much everything at this point and I think I'm losing this battle. My 95 f-150 302 5 speed just doesn't want to seem to run right and right at this moment it's down again.

It has always had a shake to it that comes and goes but for the most part I kind of concurred it up until last weekend. It started to have a hesitation were it almost felt like the ignition was cutting in and out under light throttle which bucked me around the cab and made me look like an idiot to passerby's (at least the others got a chuckle out of it) which was quite embarrassing. When I would come to a stop the truck would rev up and down and again made me look like a 16 year old to the others at the lights. When I am coasting in a gear, the throttle has a mind of it's own and feels like someone else is randomly pressing the gas very quick and letting go right after which again bucks me around. When I push the clutch in when coasting, the idle sits at a very rough feeling 1400rpm and the engine light comes on which I can make go away by flooring it.

In the last 3 months I have replaced the following:
-cap
-rotor
-plugs
-wires
-coil
-MAP sensor
-TPS sensor
-IAC
-re-done every vacuum line
-cleaned and resealed TB
-battery
-alternator
-fan clutch
-belt tensioner and pulley
-checked compression (almost perfect)
-checked vacuum (strong and steady)
-re-set timing to 10 degrees btdc
-fuel filter

Now last Sunday when it started doing it's random throttle and bucking/hesitation, I put the new tps sensor on it as well as fixed the last few vacuum lines behind the motor, and cleaned/re-sealed the TB. I disconnected the battery while doing this as well as took the sensor off the top of the egr and made sure the valve was nice and smooth with no sticking which it was. When I hooked everything back up and started it, it ran like a dream. There was zero shaking/vibrations, had a ton more power, especially in the upper rpms as well as sounded much louder through the intake with a nice whistle as part throttle (custom made intake). I went to Timmy's and back which was a 15 minute drive and was so pleased. I went to bed excited for the next day because I finally fixed her and wanted to drive it again. I go out and start it up the next day and all is well for about the first 20 min, then out of nowhere it felt like I ran over an elephant the hesitation was so bad while cruising in 2nd. It was so violent that it broke my left engine mount clean in half and almost put my chest through the steering wheel. Since then it is running even worse with an almost constant jumping idle and a hesitation/power cut every 3 seconds of driving. The engine light is back on unless I hammer the gas and it pulls pretty hard again and doesn't do anything out of the ordinary until I go to part throttle, or come to a stop/idle. It's at my friends shop right now and he can't seem to figure out what's causing this and I'm at a total loss.

Can anyone shed some light on this or maybe recommend a fix that worked for them. Sorry for the novel I just don't like to leave things out so your left guessing the rest. Ohh and the random engine light isn't leaving any codes which is strange other than a engine/balance message (snap-on reader).

Will

 

First clue would be the check engine light. Check the codes, both KOEO (key on engine off) and KOER (key on engine running).

 

Paper clip and start counting the codes. Otherwise is your od off light blinking at you?

 

You said it has a custom intake? Take it off and put the stock intake back on and see if that helps.

I would look at your mass air flow sensor as well. Sometimes a intake can mess them up, especially if you have a air filter that has oil on it and it has been over oiled. Look at the little wire that runs across and make sure it is clean and still there.

 

With any computer-controlled engine, first thing to do is pull the codes.

This is an OBD-I system and you have three sets of codes:

KOEO
CM
KOER

The order in which they appear is important as is from which test they appear.

You will get a Code 111 in the KOEO and KOER tests if the computer thinks all is well.

Post the codes you get from all 3 sections.

 

I said in post near the bottom that I pulled codes and the only thing it left was a engine/balance message after a full inspection and engine test with the snap-on computer. My truck is a non maf truck and my intake is a pretty well made one consisting of a afe totally inclosed box and self welded aluminum piping with my own design dual snorkel coming out each side of the grill.

 

I've narrowed it down to injectors or computer. We played with it all last night and tested the vacuum again which was very strong, checked all the grounds and re-did them all to the negative on the battery, put another new tps and iac in, checked fuel pressure which was good (put a new fpr 2 weeks ago), checked all fuses, and re-did the line going to the purge valve from the back of the truck seeing as how it was rotted completely. Would a faulty computer explain the engine light and random ignition/fuel cuts with-out leaving codes? Anyone had a similar experience with bad injectors causing the fluctuating idle, hesitation, idle/rev hang, and general roughness that pretty much goes away when I floor it?

 

Could a faulty tfi module or bad distributor cause this? Any tests to do?

 

tfi usually just fails, but the dizzy could be suspect. Not sure of a test off the top of my head, I'll look at my manual later.

 

I'd check the codes again.

Barring any new info from that, I'd do a full-blown compression test. If you're breaking engine mounts, it sounds like something more serious than an ignition or fueling problem.

Jason

 

I'd guess the engine/balance message is something specific to your code reader as that doesn't sound like a valid OBD-I message.

It doesn't matter if it's Snap On or Harbor Freight, something is wrong there.

You don't need a code reader, can count blinkenlights on the dash or on a test light (or sweeps of a meter's needle):

Fuel Injection Technical Library » How To Run a Self-Test

Might try one of those methods and see whatchya get.

 

Dizzy check

1. Remove the dizzy from the engine
2. Remove the TFI module from the dizzy
3. Inspect the terminals, ground screw, and stator wiring for damage - repair as needed
4. Measure the resistance of the stator assembly using an ohmmeter. If the reading is 800-975 ohms the stator is good but the TFI is bad. If the reading is less than 800 or more than 975 the stator is bad.
5. Repair as needed and install the TFI module and install the dizzy.

That's from my 87-91 Chilton's bible... Your 95 may have a remote TFI but the test should be the same.

 

This statement says that, whatever the measurement, either the stator or the TFI module is bad. What's the measurement if both are good?

Jason

 

Yes I believe I have a remote tfi on the fender-well. My friend said there's nothing wrong with the tfi because the truck wouldn't start if it was gone. He thinks that maybe my distributor shaft might be magnetized? I've never heard of that one but I'll humor the thought if it solves the problem. I'll keep plugging away at it today and post updates.

 

Any time the MIL (CEL) comes on you have codes stored in the PCM computer.
I would get rid of the snap-on reader and get a good $30.00 reader that will tell you what is wrong.
Every time I have seen a post on here that says they used a snap-on reader it was sending them down the wrong track.
A paper clip is better than that snap-on reader if you do not know how to use it. As I recall you have to have the right module plugged into a snap-on reader to get it to even work right for the truck you are hooked too.

You are reading something other than an engine/balance message as you have to go into the engine/balance test to even get the codes for it.

Also how did you replace the MAP sensor when it does not even have one?