Jump to content



Photo

3000gt sputter at WOT


  • Please log in to reply
11 replies to this topic

#1 seagull369

 
seagull369

    Advanced Member

  • Members
  • 104 posts
 

Posted 13 December 2014 - 03:37 PM

A friend of mines 1994 3000gt non turbo is having an issue with engine sputter at wot, Specifically, the engine fails to climb above around 4k rpm when the accelerator is fully depressed. This happens whether under load or just revving in neutral,  The sputter sounds like an engine whose carburetor is out of adjustment and there is noticeable power loss while on the road. Interestingly, the engine has no trouble reaching redline (and runs fine) when the throttle is gradually increased,

 

Thinking it might be the tps, I tried to adjust it via the service manual instructions but wasn't able to fit my feeler gauge against the set screw and throttle lever. Instead, I moved the tps in small increments, each time checking to see if the sputter went away. No change. I then swapped in a known working tps and did the same routine, Again, no change .

 

Might anyone have a suggestion on what could be going on? The cel isn't on, so I don't know if checking the codes would yield any info,



#2 Karrpilot

 
Karrpilot

    STAFF

  • Staff
  • 6,070 posts
  • Gender:Male
  • Location:Chicago Zone
  • Interests:Ex Ford Tech 22 years.
 

Posted 13 December 2014 - 03:48 PM

I would lean towards a fuel system problem. Filter partially plugged, pump on it's last legs, etc. But my major concern would be the vehicle age. How in the hell did a Must Be Shitty make it 20 years? The repair is going to cost more than the value of the ride. Tell the owner to see a new vehicle showroom.)

No longer working at dealerships. Government employee. Now i get paid to fix Fords.
ASE master tech
Private Pilot High Performance / Complex Rating.


#3 fullsizeblazin

 
fullsizeblazin

    Screwed by Car Dealers

  • Members
  • 3,065 posts
  • Gender:Male
  • Interests:Motorcycles, Dirt and street. Spreading the truth about Stealerships
    Since the automotive industry killed my interest in cars,...

    Life is hard. It's even Harder if you're stupid.
 

Posted 13 December 2014 - 06:15 PM

Install a vacuum gauge on it. Might be an exhaust restriction.

#4 seagull369

 
seagull369

    Advanced Member

  • Members
  • 104 posts
 

Posted 14 December 2014 - 01:48 AM

Thanks for the quick replies, guys.

 

It's interesting you should mention the exhaust restriction, fullblazing. we recently had the exhaust headers off and the rear exhaust pipe laying on the ground for a couple of days as we were changing the rack and pinon steering unit on the car. I will perform a vacuum test to see what it shows. Might even pull the headers off and run the motor to see if it improves, as well.

 

A clogged fuel filter or bad pump crossed my mind as well, karrpilot,  We have a replacement pump on hand, but the bolts holding the current pump housing to the tank are seriously rusted so we've held off changing it for now. We have a new fuel filter on order and it should be in tomorrow.

 

My friend has a loyalty to this car that defies reason. If it were the vr4 model or, heck, even had a manual transmission in it I could maybe understand but it is what it is, He's still my bud and  I'm just trying to help him out,

 

I'll let you know how it goes and if you happen to think of any other possibilties, I'd be most interested to hear about 'em.

 

Thanks again,



#5 Karrpilot

 
Karrpilot

    STAFF

  • Staff
  • 6,070 posts
  • Gender:Male
  • Location:Chicago Zone
  • Interests:Ex Ford Tech 22 years.
 

Posted 14 December 2014 - 10:11 AM

Your friend isn't the only one out there that has a love affair with a junk. My cousin's wife had one with her 1985 V W. When the rear springs / struts gave way and came up through the rear deck, she asked me about fixing it. I took one look at it, and gave her the phone number to my favorite junk yard. There was NO fixing it.

 

She got all pissed off at me, had the pile towed home, and proceeded to try and find a body shop in the area willing to take on such a project. With no luck. A year later, said vehicle did indeed go away.

 

I myself drove a Bronco 2 with a cracked cylinder head for a year before dumping it. That wasn't because I had any love for it. It was because I was paid flat rape, and eating was higher priority.


No longer working at dealerships. Government employee. Now i get paid to fix Fords.
ASE master tech
Private Pilot High Performance / Complex Rating.


#6 fullsizeblazin

 
fullsizeblazin

    Screwed by Car Dealers

  • Members
  • 3,065 posts
  • Gender:Male
  • Interests:Motorcycles, Dirt and street. Spreading the truth about Stealerships
    Since the automotive industry killed my interest in cars,...

    Life is hard. It's even Harder if you're stupid.
 

Posted 14 December 2014 - 09:58 PM

Yup. Had me a late 80's Civic that had worn piston rings and drank a quart of 20w50/week. Paid on flat rape, I used junk yard parts to keep it alive. I eventually wised up, sold it for $500 more than I bought it for to ricer kids and bought my S10. The Stealership made sure they did everything in their power to prevent me from living above the poverty level.

#7 seagull369

 
seagull369

    Advanced Member

  • Members
  • 104 posts
 

Posted 16 December 2014 - 05:26 PM

Well, I disconnected the exhaust post-cat and also changed the fuel filter and neither had any effect, I disconnected the plug going to the MAF sensor and the problem went away. At WOT engine revved to redline no trouble, Sprayed the MAF wire with cleaner and reinstalled with plug back in and same problem, Electrical pins on connector and MAF look good. Wires to connector look OK. The intake hose and air box have no leaks.

 

Would it be safe to assume the MAF is bad?



#8 fullsizeblazin

 
fullsizeblazin

    Screwed by Car Dealers

  • Members
  • 3,065 posts
  • Gender:Male
  • Interests:Motorcycles, Dirt and street. Spreading the truth about Stealerships
    Since the automotive industry killed my interest in cars,...

    Life is hard. It's even Harder if you're stupid.
 

Posted 16 December 2014 - 07:53 PM

If the problem goes away after disconnecting the MAF it would almost be safe to assume it is the MAF. To be sure, you'd have to have a scan tool and read the MAF PIDs to check what it's reading and compare to specs. Try one.

#9 Karrpilot

 
Karrpilot

    STAFF

  • Staff
  • 6,070 posts
  • Gender:Male
  • Location:Chicago Zone
  • Interests:Ex Ford Tech 22 years.
 

Posted 16 December 2014 - 09:25 PM

I had a MAF go bad on grand ma's 1995 LTD do all kinds of weird stuff. I wrote down the readings, then compared said reading to a new 2011 LTD that ran great. Then I got out the shop manual chart.

 

Seems that grand ma's car thought it was up in Denver, due to the BARO reading I got off of it. That one didn't want to clean up either. A Ford reman MAF took care of it.

 

If you can't find a OEM unit, try at least to use a NAPA one. Getting one from Auto Drone, and you might go through a handful before you get a good one.


No longer working at dealerships. Government employee. Now i get paid to fix Fords.
ASE master tech
Private Pilot High Performance / Complex Rating.


#10 seagull369

 
seagull369

    Advanced Member

  • Members
  • 104 posts
 

Posted 17 December 2014 - 01:31 AM

I don't have the tools or know-how, frankly, to diagnose the booger, so I ordered a "loaner" MAF from said Auto Drone which should be in tomorrow.

 

I had a bright idea after writing my post here to go spray the wire again, but this time with brake cleaner. :blink:. Yea,,, didn't turn out good...

 

Will keep u posted and thanks.



#11 meme

 
meme

    Advanced Member

  • Members
  • 159 posts
  • Gender:Male
  • Location:PA
  • Interests:sure as hell isnt cars.....thats my job
 

Posted 17 December 2014 - 07:31 AM

its not the MAF  ,when mitsus see the MAF unhooked ,the computer defaults too full fuel pressure. so you now know the pump,is capable,and the filter is fine.  but its definatly,a fuel issue.    huge guess here,  if it has over 100k,  the PCM, is the more likley cause. if you have no communication, with the factory scan tool, it's definatly the PCM



#12 toddrs93

 
toddrs93

    Newbie

  • Members
  • 1 posts
 

Posted 17 December 2015 - 01:46 PM

One year old.. was this ever figured out?  fyi 99% of the time there were no issues with 2nd gen pcm's (94 up). Only the 91-93 pcms all had problems (leaking capacitors)




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users