mx83 1uz swap starts no idle

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ratchetasscressida

New Member
Messages
3
sooo i’ve put a 93 sc400 1uz in my 91 cressida, i got the harness done by a shop and they came by again today to make sure the wiring isn’t the issue, so, the car starts up strong revs to about 1500 and shuts off. it runs the same amount of time everytime, i’ve ran codes i only got some for o2 sensors since they’re not plugged in as i’m still figuring out how to run the header around the steering rack, any advice is appreciated!
 

Zuffen

Super Moderator
Staff member
Messages
5,402
Location
Sydney, Australia
Are you sure the fuel pump isn't turning off?

The fuel pump goes into high speed to start then drops to a slower speed.

I had it once where the low speed resistor (On a Crown engine) was faulty and it had similar symptoms.

Bypassed the resistor and all was good.
 

ratchetasscressida

New Member
Messages
3
Are you sure the fuel pump isn't turning off?

The fuel pump goes into high speed to start then drops to a slower speed.

I had it once where the low speed resistor (On a Crown engine) was faulty and it had similar symptoms.

Bypassed the resistor and all was good.
yeah we tested the fuel pump today and it’s all good
 

ratchetasscressida

New Member
Messages
3
Are you sure the fuel pump isn't turning off?

The fuel pump goes into high speed to start then drops to a slower speed.

I had it once where the low speed resistor (On a Crown engine) was faulty and it had similar symptoms.

Bypassed the resistor and all was good.
i’m thinking maybe clogged injectors?
 

Zuffen

Super Moderator
Staff member
Messages
5,402
Location
Sydney, Australia
Are you testing it when it is running to see it doesn't stop.

Once the engine stops and you turn on the ignition it will revert to hi speed.
 

gloverman

Well-Known Member
Messages
2,979
Location
Hamilton. New Zealand
Then as part of my diagnostic I often look at this. Its the same as code 14 & 15 which it can have the fault for but dont always display the code. I would also be checking for seized injectors. Just the basic stuff. Confirming ecu is good is also a good idea.
 

361UZ

Member
Messages
137
Location
Canberra ACT
First suggestion? Watch Groverman's video above! Learn that there are many reasons an engine will stop. In his case a seemingly unrelated fault was causing the fail safe systems to cut the fuel, even though it was an ignition fault.
Do you have the diagnostic plug and check engine light connected? Can you read the failure codes? Do it. As soon as it stops, read the codes (some are cleared by a sucessful start).
Could be fuel or ignition.
Best way to check the fuel pump is to monitor fuel pressure (if you can) or somehow monitor the fuel return line to the tank to make sure the fuel is returning (so is still feeding the engine). Similarly to Zuffen, I originally had a Commodore VL Turbo pump on my Crown. Ran fine till it failed. I replaced it with a more powerful pump. Then the engine wouldn't idle when it was hot. Reason was the new pump drew more current than the original pump I had, so it wouldn't run at low speed. High speed it was ok.
See the video on how to run the engine on starting fluid. See the video on how to check for spark while the engine is running (and stopping in your case).

Have fun.
 
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