Tech Heads - Rough Idle / No Power

[williammoore]

This is a difficult question for all you amazing tech Heads out there.

My 1997 4.0 Sohc Explorer is running rough from the second you start it, You put your foot on the gas and it pulls away but about as twice as fast as usual.

Ford have had it for 5 weeks and still no joy. They replaced plugs, leads, throttle body, checked timing, changed inlet manifold gaskets and still no luck (they didn't charge me for any work as they didn't solve the problem and didn't know how to). It coughs every few seconds when idling and worse when put into drive (nearly stalls). Thought it could be IAC but tried another from an Explorer that was running ok (I did reset the computer before running it) - but still no luck. Checked the MAF (so did Ford), Air temp sensor, CKP and secondary resistance on the coil pack, - all ok exept for the camshaft postition sensor which should read about 1.5 volts - this was only showing 0.2 volts ??

The o2 sensors were replaced about 4 months ago but acording to my manual the computer ignores these until they are at operating temp so it can't be them as this does it from cold.

It goes through gas at about 10 mpg aswell. The exhaust doesn't sound as powerful - could this be a blocked cat ??? (it isn't glow red or anything though.

p.s. this was not a gradual thing but happened the next day I drove it.

I would hope someone out there could help

Kind regards

Willie

 

[dre2013]

subscribing...my 96 4.0 has the same problem..it actually cut off yesterday with the a/c on while idling at the gas station! i put it in the shop this morning to get the 4x4 serviced but this problem still bothers me.

 

[williammoore]

Hope your garage can fix yours ok as I'm running out of options here in the uk

 

[ffejeroni]

I don't know if this may help, but check the idle air control motor. That is what my problem is (same conditions) I am fixing it this weekend. It's about a $50 or so part (in the US). Good luck!

 

[williammoore]

Just wondering, could it be my PCM as I thought I would unplug the MAF whilst running to see if the PCM would go into emergency mode - no light came on on the dash and the car still ran like crap still

 

[williammoore]

Checked the IAC, getting voltage and the right resistance according to the manual - could it still be faulty ??

 

[exploded99]

Well, you've been through the upper part of the engine pretty thoroughly. I think its time to do a compression test or cylinder leakdown test and eliminate or confirm a bad valve. That cough could be a valve.

You've tried two IAC's - seems very unlikely that has anything to do with your problem.

I do not know if a low reading on a camshaft position sensor can cause your problem. Others will have to chime in on that.

Pretty nice of Ford not to charge you - The dealers over here charge you whether they fixed it or not. But I am a little puzzled they have not checked compression.

 

[williammoore]

Will have to get the compression test done (Ford couldn't even tell me what bank of cylinders were causing the problem) - thanks

 

[exploded99]

Well, I realized you had not mentioned fuel injectors. Do not know how long since you've cleaned your injectors, but if you can find BG44K try a can. (24 dollars U.S.) or another high quality cleaner. Concentrate what you use to a half tank of gas.

Also, fuel filter fuel change and pressure checks were not mentioned. I am throwing some ideas out here - not entirely convinced they match up to your symptoms. But I would go through the fuel system since you have beat up the electrical side pretty hard.

Another idea would be a stuck / sticking lifter. That is another cough producer. That one is kind of tough to nail down. There are some engine flushers that are very volatile that remove varnishes and gum from the engine. You must immediately change your oil after using them.

I am guessing your dealer does not have the electronic engine analyzer to hook up to your PCM ? Is that why they could not tell you which bank was ill?

Also, the old vacuum gauge may be useful here. A good mechanic and a vacuum gauge can tell you a lot.

Do the cleaners yourself and see if they help. Buy the good stuff. Then move up to the more expensive tests.

That should be enough to keep you out of trouble this weekend. Good luck!

 

[williammoore]

Fuel filter was changed, injector cleaner run through system, fuel pressure ok, checker egr. Ford hooked it up to their machine but told me it wasn't 100% compatable with the Explorer ???. But you have given me some ideas to go on thanks - will keep posted

 

[94ZebraRanger]

can someone tell me where the IAC is located. So I can check mine.

Tim

 

[williammoore]

mines under the plastic cover on the top of the engine but I am not sure where yours is as yours is a 4.0 Pushrod Engine but I think it should be in the same place (silver coloured cylindrical with two wires coming from it.

 

[Exploress]

I just purchase some sort of power booster if you will that gives my eddie bauer the power of a v8 instead of a v6. It is basically just a wire that plugs into the IAC and costs about 5 bucks off of ebay. It does not damage the computer and really gave mine a boost. Just thought you'd like to know.

Checked the IAC, getting voltage and the right resistance according to the manual - could it still be faulty ??

 

[exploded99]

Did that vacuum gauge tell you anything?

 

[Howard]

My guess is that it has to do with the fuel system. Sounds like the engine is getting excessive fuel. Have the fuel pressure release valve checked as it may be stuck. BTW Ford garages here do not understand the explorer and do not have all the service details or tools for them.

 

[williammoore]

Ford Garages in the UK are useless plus even Ford UK Technical don't have a clue at all but will keep testing and trying things myself will keep posted - Many thanks Guys

 

[williammoore]

Got news at last, Took the front off the engine and the left rocker cover - found the left camshaft chain cassette in pieces plus the main timing chain tensioner (the one between the crankshaft and Jackshaft) was practicly non existant so now in the middle of repairs. Thanks for all your help plus does anyone know how to reset the timing as when you remove the camshaft chain there are no timing marks.

Willie

 

[Howard]

Special tools are used to lock the camshaft and crankshaft in position. The Haynes manual gives details of the procedure.
http://www.otctools.com/newcatalog/products/314_bro.pdf

 

[exploded99]

Well thanks for posting the answer back. I was curious.

I believe that is an interference engine - so its a good thing you kept after your problem. Would have been a LOT more expensive to fix.

 

[williammoore]

Well thats it finally complete and it runs like a dream, just got to free the brakes off where it has been sitting around. Got a picture of the special timing tool from a garage as I could not source THE TOOL one in the uk, made my own tool up and there we go. THANKS EVERYONE FOR THE HELP.