89 Supra Idles Rough and Drives Rougher

[RCAttack]

My 89 Supra Idles rough intermittently and also while driving wants to stall but actually never does. When it begins to die if you push the accelerator to the floor the engine will slowly catch back up..... The only thing that has changed from it running fine and then running horrible is that I ran the fuel tank completly empty. Could these symptoms be caused by a clogged fuel filter? Yes, the plugs and wires were changed Saturday and the ISC was checked. Any suggestions to the cause?

Thanks,
Daniel

 

[mkiii222]

Clogged filter or shot fuel pump.

If all that happened between running decently and running rough/stalling is that you ran it past E then you probably picked some sediment off the bottom of the tank.

Toyota fuel filters are 'supposed' to last forever but realistically it's more like 100-150k.

 

[RCAttack]

This filter is a Fram and I would be willing to bet it is clogged. The fuel pump seems to be working i jumpered it off and it made a gurgling noise as specified in the Haynes Manual. Is there an easy way to acess the filter?
Thanks

 

[Dirgle]

Fram filters are horrible and could create problems for you. Toyota intentionally put the fuel filter in an extremely difficult to access area so people would quite trying to change them at regular service intervals. They did this when they switched to lifetime filters.

 

[JStoked]

I am having the same problem. But I put a napa filter in mine they said
it was oem. But mine is hard to start iv got to hold the pedel to the floor
to start it then it won't idle till it gets warm. Pretty sure it's not the filter.

 

[mkiii222]

Fram filters are horrible and could create problems for you. Toyota intentionally put the fuel filter in an extremely difficult to access area so people would quite trying to change them at regular service intervals. They did this when they switched to lifetime filters.

+1 on the Fram being junk but -1 on the 'lifetime' filters. Every Toyota filter I've seen needs to be changed somewhere around 150k.

Get a Toyota/Denso filter. And no, there isn't an easy way to swap it. You will drip fuel so have some rags handy.

 

[Dirgle]

I'm at 190,000 and it's not an issue..........yet. The lifetime comment was more directed at why they put it in such a difficult place, not the actual service life of the filter.

 

[hvyman]

250k on orig fuel filter. Shit wont come off even if i wanted to change it.

 

[rodama5anthony]

250k on orig fuel filter. Shit wont come off even if i wanted to change it.

ohhh i had the same problem struggled with that piece of shit for over an hour almost pulled a hernia

 

[hvyman]

I just gave up since i didnt have all my tools with me. To lazy now and its not going to help anything.

 

[RCAttack]

It seems it it sucking too much air...... I took the air filter off and put my hand over the intake and she idles perfect...... Is there a fuse that is connected to the airflow sensor? Could the airflow sensor go bad?

Thanks

 

[7thousandpiecesMGTE]

I would check for codes, then make 100% sure you do not have any vaccum leaks before anything else.

Code 31 will tell you if your afm is bad. I do not think the AFM is fused anywhere, pretty sure it is grounded and the rest of the wires go straight to the ecu.

 

[RCAttack]

No vaccum leaks found. Ill drop a used Airflow Sensor In it of my 90 n/a that sits down beside my out buildings with a possible BHG....... They are the same right? They appear the same and have the same connectors

---------- Post added at 08:59 PM ---------- Previous post was at 08:59 PM ----------

out of**

 

[Dirgle]

Nope, afraid the're not interchangeable. One uses a flapper door to meter airflow and the other uses KV meter. The out put two very different signals to the ecru.

 

[gottadiesel]

I am having the same problem. But I put a napa filter in mine they said
it was oem. But mine is hard to start iv got to hold the pedel to the floor
to start it then it won't idle till it gets warm. Pretty sure it's not the filter.

Sorry to OP - But since Jstoked made the comment, figure I could add a suggestion in regards to his issue... Your issue sounds like it might be an issue with your cold start injector... It adds extra fuel during cold start and IIRC continues to add some until temp reaches a particular set point. The not idling can also be an issue with your idle control valve, but I do not think it would affect the having to add more fuel to get it to start...

 

[boostcraver]

250k on orig fuel filter. Shit wont come off even if i wanted to change it.

Second that on the "won't come off" part. Thing is mine sat with old gas in it for something like five years before I got it and if the gas in the filter looks anything like the gas in the tank did when I dropped it to clean/drain, it def needs a change. Oh, and I'm sitting at 160k+

 

[Chaingun]

I ran into a very similar issue about a week ago, i had just changed plugs and after putting everything back together i drove about 25 miles to my parents place, as soon as i got into town the idle went to hell and the car would not rev past 1300 or so without getting choppy. Turns out one of my intake hoses between the IC and manifold came loose not enough to blow the tube off but enough to leak massive amounts of air. Every car i've ever had from a big block 454 to a 2.2L Cavalier that has had idle issues i traced back to an intake leak, may not be the case with yours but i'd do a double check of vacuum hoses and gaskets at the EGR and such.

 

[7thousandpiecesMGTE]

Did you check for codes? Your AFM might not be the cause, in my opinion there is no sense in hunting one down to test in you car if you dont have a code saying its bad... even if your check engine light does not stay on the ecu will still store codes that may help you diagnose your problem.

http://www.cygnusx1.net/Supra/TechTips/engine_error_codes.aspx

How did you check for vacuum leaks? The most definitive way I have learned to know for sure if you have a vacuum leak is to disconnect the air hose from the PCV and Idle Speed Control Valve, start the car and then cap or plug them off, this should cut all air supply to the motor and it should die (if the throttle plate is fully closed). If it doesn't it is getting air from somewhere its not supposed to, which would be a leak. Once you know you have a leak then you can do the visual and starter fluid methods to try and find it.