Fuel Cut disable/delete??? ST185

Write ups and tutorials for maintenance and modifications.

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Wed Jun 05, 2019 9:25 am

It feels like it is cutting the fuel a bit, but it runs too rich. It has no problem getting up to 1bar of boost, it just shakes alot because of the rich mixture of fuel or it cuts the fuel or something Else. It accelerates good until i reach 0,7bar and then it struggles a bit to keep accelerate.
What do you mean by CEL? and if there is any codes?? Do you mean "check engine" codes?

Yesterday the engine light came on. Dont know why... I turned the car of, took off the battery for a couple of mintes, but the check engine light didn't go away. So it is now at home with no battery hoping that it will dissapear.
Also when i parked i looked in the engine and saw the turbo was red hot :o dont know if this is normal with these cars or if that could be the cause of the check engine light?
Members don't see the above ad. Register now - it's free!
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby underscore » Wed Jun 05, 2019 5:04 pm

Selsvik wrote:It feels like it is cutting the fuel a bit, but it runs too rich. It has no problem getting up to 1bar of boost, it just shakes alot because of the rich mixture of fuel or it cuts the fuel or something Else. It accelerates good until i reach 0,7bar and then it struggles a bit to keep accelerate.


Sounds like it's either getting too much fuel or it's losing air somewhere or the computer is detecting a problem and pulling timing. Or the computer itself is having problems, given the age of them they're all due for having the capacitors replaced as they will start to leak (can cause even more damage) or dry out.

Selsvik wrote:What do you mean by CEL? and if there is any codes?? Do you mean "check engine" codes?


Yes, the light is supposed to come on with the key turned on (not running), then once started it should turn off. If it isn't doing that you've got a problem with the bulb or the wiring or the ECU. If it is working correctly then check for any codes (the list of codes is around here somewhere) and go from there.

Selsvik wrote:Yesterday the engine light came on. Dont know why... I turned the car of, took off the battery for a couple of mintes, but the check engine light didn't go away. So it is now at home with no battery hoping that it will dissapear.
Also when i parked i looked in the engine and saw the turbo was red hot :o dont know if this is normal with these cars or if that could be the cause of the check engine light?


Why are you trying to get rid of a diagnostic code that could be telling you what the problem is? Always read the codes before clearing them. The light is telling you the computer detected a problem and it has a code for you to tell you what that is.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
underscore
GTFour God
 
Posts: 4307
Images: 0
Joined: Mon Apr 09, 2007 11:29 pm
Location: Kelowna, BC

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Wed Jun 05, 2019 8:42 pm

That is actually a valid point... I have an appointment on friday at the workshop(Toyota). Maybe they can look what the code was for. I've heard that the ecu has all check engine codes saved in their memory (Y)
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby underscore » Thu Jun 06, 2019 4:24 am

It stores any codes that have come up (even if the CEL is currently off) as long as there is power to the ECU. If power is removed they get cleared.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
underscore
GTFour God
 
Posts: 4307
Images: 0
Joined: Mon Apr 09, 2007 11:29 pm
Location: Kelowna, BC

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Tue Jun 18, 2019 5:43 pm

Small update... The workshop found out that the engine light was the knock sensor. They think that it has been set off because of all the shaking from the rich mixture.

Then i found a possible leakage, and fixed it. It now runs on 10-11 instead of 8-9 when full throttle.
So thats good. But it still runs a bit rich, and the engine light wont go away...
And after the engine light has Come, it runs really bad... So im Wondering if anything has happened when the knock sensor went off.
Last edited by Selsvik on Wed Jun 19, 2019 9:28 am, edited 1 time in total.
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby underscore » Tue Jun 18, 2019 7:40 pm

I've dealt with the knock system far more than I cared to while troubleshooting my car. The wire can be internally shorted or broken, this can be tested with a multimeter. The sensor itself can also fail and not send any signal, either right away or once warmed up a bit. In the end I replaced the wiring all the way from the sensor to the ECU twice (be sure to use correctly shielded wire, or you can steal the wiring from another Toyota) and replaced the sensor twice and I haven't had an issue since. When the sensor cut out randomly when warm I'd have to clutch in, shut the engine off, restart, clutch out and keep going til it happened again which is a REALLY annoying way to get around town.

A friend with a turbo MR2 also had knock issues, he kept replacing the sensor before figuring out sloppy motor mounts were causing the problem, so make sure there isn't too much play in those.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
underscore
GTFour God
 
Posts: 4307
Images: 0
Joined: Mon Apr 09, 2007 11:29 pm
Location: Kelowna, BC

Re: Fuel Cut disable/delete??? ST185

Postby sefiroxx » Tue Jun 18, 2019 7:54 pm

Symptoms of misfire/knocks are common when AFR is off due to air or fuel leaks. It's possible the knock sensor or pigtail is going.

The high idle readings are indicating a lean condition most likely a air leak (or clogged injector).
User avatar
sefiroxx
Club Member
 
Posts: 66
Joined: Thu Jul 21, 2016 5:43 pm

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Tue Jun 18, 2019 8:34 pm

Yes, the lean mixture when idle was a hose that had came off. But i fixed that. So it idles around 14,7 now.
Must be another leakage on the vacum hoses... Tested the air Flow meter, no problem with that...
But what do you mean by "It's possible the knock sensor or pigtail is going." ?
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Tue Jun 18, 2019 8:50 pm

I will check with these engine mounts! I recently changed the rear diff Bush to a poly Bush. Its really stiff. And i can feel the car is shaking i bit because of that. So i will check that out too (y)
Last edited by Selsvik on Wed Jun 19, 2019 9:31 am, edited 1 time in total.
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby underscore » Tue Jun 18, 2019 9:17 pm

If the sensor is failing, or the wiring is faulty, the ECU assumes worst case scenario and pulls timing, dumps loads of fuel, etc and basically becomes as safe as possible but also absolutely gutless.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
underscore
GTFour God
 
Posts: 4307
Images: 0
Joined: Mon Apr 09, 2007 11:29 pm
Location: Kelowna, BC

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Mon Jun 24, 2019 5:58 pm

when i start up the car, it does not idle "correct", and the check engine light does not appear until about 1900rpm...
so i dont know if that means that the sensor is failing or if it is working and detects a problem... :shrug:
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby underscore » Mon Jun 24, 2019 10:08 pm

At low RPM the ECU doesn't check the knock circuit. The easy check is using a multimeter at the ECU plug, check if the wire for the knock sensor is shorted to ground. If yes replace the wiring, if no get access to the knock sensor and check for continuity from the plug to the ECU. If it's good replace the sensor, if it's broken replace the wiring. Be sure to use shielded wire and properly ground the shield (only at one end! that part is absolutely critical) if you replace it.
★ 1991 GTFour RC ~ "Rebel Scum" ★
It's for sale! http://www.alltrac.net/phpBB2/viewtopic.php?f=64&t=52181
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
underscore
GTFour God
 
Posts: 4307
Images: 0
Joined: Mon Apr 09, 2007 11:29 pm
Location: Kelowna, BC

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Mon Jun 24, 2019 10:16 pm

Ok, i will try that out thanks!! :)
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Sat Aug 17, 2019 4:46 pm

Small update since last.
*I replaced the knock sensor and the check engine light dissapeared. :))) turns out that the sensor was faulty.
So the car runs alot better now, but still not perfect.
*I found out that the EGR was leaking exhaust, so i blocked it! Works better after that.
*And i found an air pressure leakage, so fixed that as well.

Whenever i boost up to like 0,5bar or higher, it feels like fuel cut. it shakes alot and does not want to go faster.
But i disconnected the MAP sensor entirely(just plugged the pressure hose), so i dont see how that can be it...(?)
i also tried to turn the boos to a minimum, still won't run good when full boost.

And when i have been driving for a little while and stops, the car wont idle perfect. it goes up and down on RPM.

I recently changed back to the original air filter box just to see if that made a difference.

*Recently changed spark plugs (original Toyota parts)
*installed Oil Catch Can

i am this close to giving up and just sell the car... :/
please help :)
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

Re: Fuel Cut disable/delete??? ST185

Postby Selsvik » Sat Aug 17, 2019 5:19 pm

So this is the Map Sensor, right?
so what i did to disable the fuel cut, was to disconnect the vacuum/pressure hose that was connected underneath the sensor, and plugged it. i haven't done anything else with the sensor.
this is the way to do it, am i right?
You do not have the required permissions to view the files attached to this post.
Toyota Celica ST185 AllTrac
Selsvik
Club Member
 
Posts: 38
Joined: Sun Oct 28, 2018 8:02 pm

PreviousNext

Return to How To

Who is online

Users browsing this forum: No registered users and 1 guest

cron