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Rb25det s1.5 rich idle/misfire 2k+

3thn5
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3thn5 Newbie

3thn5

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Hey guys have a 94/95 33 gtst with a rb25det in it, stock apart from, fmic, Toyota Yaris coil pack mod, ems 8860 computer, 3inch exhaust, walbro 255Lph pump. 
 

now to my problem, 2 weeks ago I wasn’t getting any luck starting the car, bought a walbro 255 Lph fuel pump installed that, still had no luck starting the car, replaced coil pack plug connectors and remade the harness, car now starts yay :) but it idles very very rich, Tech edge Afr fuel guage reads ‘rich’ lumpy idle heaps of black smoko coming from the exhaust. Installed an adjustable fuel pressure regulator set the psi to 20, car ran a lot smoother but still read ‘rich’ on afr and black smoke out of the exhaust, have changed the spark plugs over, have triple checked vacuum lines can’t find any unplugged or splits in the lines, cleaned iacv, cleaned maf sensor even tried a friends still didn’t work, does anyone have any ideas of what it could be or where else to check I’m losing my sanity, cheers heaps 

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robbo_rb180 Grand Master

robbo_rb180

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Posted

What diagnosis did you do to determine faulty fuel pump?
Adjusting the reg that low will cause problems.

go back and...
set fuel base pressure to 45psi
install fresh plugs
Connect to the ecu
Check to see if all connected sensors to ecu are giving correct readings
If not replace faulty sensor

Idle afr should be around 14.7 doesn't have to be exact. 

If this is beyond your skill set find a decent shop to look at it and sort it

 

robbo_rb180 Grand Master

robbo_rb180

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Posted
On 4/28/2022 at 9:34 PM, Ben C34 said:

Car out of no where runs mega rich, and you have changed regulator leaves just injectors and ecu.

Or intake air temp sensor. Starting with easiest what is your intake air temp ?

IAT or TPS would be my thinking or "Was running fine than I replaced this and that now it has an issue"

3thn5 Newbie

3thn5

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On 28/04/2022 at 9:37 PM, robbo_rb180 said:

What diagnosis did you do to determine faulty fuel pump?
Adjusting the reg that low will cause problems.

go back and...
set fuel base pressure to 45psi
install fresh plugs
Connect to the ecu
Check to see if all connected sensors to ecu are giving correct readings
If not replace faulty sensor

Idle afr should be around 14.7 doesn't have to be exact. 

If this is beyond your skill set find a decent shop to look at it and sort it

 

Couldn’t hear factory pump prime, plugs weren’t wet, replaced with new pump, can’t connect to ecu, unsure if it’s because it’s so old and no latest software updates or plug in ports damaged internally, bought a new cord to connect and no luck (EMS 8860). 
have tried letting the car idle and taking out coolant sensor all that happened is it idled abit worse but didn’t die. Also let car idle on the maf that was on it when I bought it, in plugged and car still ran, swapped with another pink maf, unplugged on idle and still ran, cleaned o2 sensors and car ran at 0.80 Lambda instead of the usual 1.0, after starting it this afternoon the afr guage reads ‘rich’ 

3thn5 Newbie

3thn5

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Posted
On 28/04/2022 at 9:34 PM, Ben C34 said:

Car out of no where runs mega rich, and you have changed regulator leaves just injectors and ecu.

Or intake air temp sensor. Starting with easiest what is your intake air temp ?

Can’t get into ecu to read if it’s set up in there but I’d say anywhere  from 25-35° cool outside but hot in the shed after abit, any way to test injectors? Family member asked if it has a cold start injector like his VL had, Is the cold start valve possibly staying open? 

robbo_rb180 Grand Master

robbo_rb180

Posted
Posted

you need a laptop with windows vista or Xp and a serial port.

Cleaning the Wideband sensor will have killed it 1 Lambda is Afr 14.7 on petrol and .8 lambda is Afr 11.7

There is no cold start valve, IAC will allow more air to pass at start up.
As stated will need to connect to ecu for sensor data but due to EMS being closed for so long, hard to find software and older laptop probably up for a whole new ecu setup.

Depends where located a decent shop may have something to access ecu, I know I do.

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