Code 542 Issues
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Code 542 Issues
I have a 94 Ranger with a 4.0 V6...no CEL...but, showing a 542 open fuel circuit code...the engine knocks under any load. has a build up of extra fluid in the crank case, and about 25% lower mpg...I had this same problem back in 9/05 with a CEL, but was supposedly resolved by a mechanic...with a MAF...I went back in 11/05 and he recommended a fuel prssure regulator at $75...may have been a waste of money...now, here we are again...should I take it back or head to the stealership...?...any suggestions...
Post Fiend
Joined: Dec 2001
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From: South Jersey
I would clear the 542 and see if it comes back.
Does the oil smell like gas? If it does see if you have gas in the vacuum line to the fuel pressure regulator after you run it for a few minutes.
Does the oil smell like gas? If it does see if you have gas in the vacuum line to the fuel pressure regulator after you run it for a few minutes.
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Thanks for your prompt reply...I changed the fuel regulator out 2 months ago at the suggestion of the mechanic who replaced the MAF this past Sept....I'll check the line to see if their is gas in the Vacuum line...what will that tell me, anyway...?
Postmaster
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From: SoCal
If theres gas in the FPR vac hose theres a leak in it & it's dumping raw gas into the intake. Or a leaking injector could dump gas in there. Has the fuel pressure been checked? Like Ken sez does the oil smell like gas?
Not sure if a 94 auto trans has a vacuum modulator, but if it does that could dump trans fluid in your engine oil.
Could also be antifreeze, is it loosing coolant?
Not sure if a 94 auto trans has a vacuum modulator, but if it does that could dump trans fluid in your engine oil.
Could also be antifreeze, is it loosing coolant?
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to 87 XLT...I think you may have hit the nail on the head...!...I thought I was burning some trany fluid, cause I could not find a leak but was having to add it at a quart or so a week...the oil in the crankcase does not smell at all like gas... hose leading into the FPR is damp at most...I'll look into the vacuum modulator deal and see what I can come up with...not loosing any coolant and not running hot...
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From: Beaver, Pennsylvania
I also have a 94 with a 4.0 Auto. Yes it does have a vacuum modulator! but don't ask a parts store. When mine went bad and went for a new one they said mine didn't have one. I checked other part stores samething, there books list no mod, after 87 or 88 so they said there was none. THERE IS ONE! passenger side near rear of trans. I had to get a modu, for an earlier year but worked fine.
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To Rags...I was able to find a Deutsch Vacuum Modulator #MV214 for $12.99...do you think that is the right one...?....so once I find one, it is located under the truck near the trans on passenger side...?...any special recs on replacement or tools...?...settings...?...when I spoke to the guy at Autozone, he said that the trans system is a closed system and that tran fluid could not get in with the oil...I hope it is not time just to give her the bullet...!...did you have trany fluid disappearing too?
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Postmaster
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From: SoCal
First thing to do is to pull the vacuum hose coming from the modulator off of the intake & see if it's wet with trans fluid.
It's about a 1/2 inch hose & plugs into manifold vacuum at the top of the engine.
It's about a 1/2 inch hose & plugs into manifold vacuum at the top of the engine.
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I took the vacuum line off the FPR and it was wet with what appeared to be trans fluid...I saw that the vacuum modulator is on the side of the trans in a really awkward spot...it looks like the cat converter wll have to be dropped down...the problem I saw is that the nuts on one end are so old and rusted, they might not come loose...the 1/2 inch hose at the top of the engine is wet as well..if I replace the vacumm modulator, is that going to prevent loss of trans fluid into the crankcase...?
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From: SoCal
The FPR on my 87 2.9 has a 8" long 1/8th inch diameter hard plastic vac hose & a fuel line plugged into it and it plugs into the fuel rail. Is that what you are looking at? The only thing that will leak from a bad FPR is fuel.
If the trans modulator is leaking, trans fluid will be sucked into the intake manifold. The modulator has a rubber diaphragm & when they rip open they leak trans fluid into the vac hose.
If the trans modulator is leaking, trans fluid will be sucked into the intake manifold. The modulator has a rubber diaphragm & when they rip open they leak trans fluid into the vac hose.
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From: Beaver, Pennsylvania
Yes the modu, is hard to get at I was able to work between the cat and trans, cold. but if you have never replaced a modu, take the cat off! When you pull the vacuum line off the old modu, trans fluid will be in the line if bad. When replacing the modu, just watch for the little rod that is behind it ( don't loose or forget to put it back )
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...couldn't get the bolts and nuts loose on the front end of the cat conv...the nuts are rusted and coroded...found some nut remover sockets and a nut craker but wasn't sure that I could reach the nut on top of the pipe on the connection to the cat converter...hope that was not it but I think it may be...took it on to the mechanic this morning...still getting a 542 code and burning too much gas...I'm not really going to get my hopes up....
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...you guys are good...!...according mechanic guy, I need a new vacuum modulator...he found fluid in the line leading out, just like you guys said...mechanic guy rec I take it to a trans shop because they could probably do it cheaper...shock, eh...?...mechanic guy said he could do it if I wanted him to...looks like I'll give it another crack...I asked him once the cat conv was taken off, what would happen if it did not get put back on,,,he said it would run fine but I might get a CEL...wish me luck on the modu replacement
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...It's finally fixed...got the vacuum modulator put in...shifts smoother and runs better...can't believe the difference already...had to buy a damaged nut remover set of sockets to get the cat conv nuts loose...glad I got the new sockets...money well spent on them..thanks again for all your help
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From: SW Va
Good to hear you finally got her fixed.
Now that the tranny fluid ingestion problem is fixed, I'd change the crankcase lube & filter & pull & check the spark plugs, as they're likely carboned up from having to process all that tranny fluid.
Probably wouldn't be a bad idea to run a can of Techron Consentrate, or Seafoam through it also, to try and clean up the combustion chamber, intake & exhaust valves, as they're likely loaded up too.
Now that the tranny fluid ingestion problem is fixed, I'd change the crankcase lube & filter & pull & check the spark plugs, as they're likely carboned up from having to process all that tranny fluid.
Probably wouldn't be a bad idea to run a can of Techron Consentrate, or Seafoam through it also, to try and clean up the combustion chamber, intake & exhaust valves, as they're likely loaded up too.
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