98 tacoma 2.7 runs when cold but engine dies when hot

LIST of things verified...
New fuel pump and filter
All sensors checked out ok
Clean throttle body
Verified spark on all plugs and coils test good


Engine with run for about 5 minutes cooled...once it gets to normal running temp it will start skipping then die. Engine will not restart untill it cools off. Im showing a p1300 code but when engine dies the fuel trims will be -100%. Im thinking i have a bad ecm... any ideas would help thanks.

 

check engine light?

 

Yes

 

For bank 1 o2 sensor heater. Surely that wouldnt cause this problem?

 

Twice in a lifetime!

@98tacoma27

 

Sounds like cold start circuit problem. I wouldn't start throwing money at other things like fuel PSI etc. yet.

 

It would cause fuel control issues. Not enough to do what your describing. The sensor heater is only used as the exhaust warms up. After a few minutes, the heat from the exhaust keeps the sensor at temperature.

When does your issue happen, at idle, acceleration? Can you tell what kind of stutter it is, from air or fuel starvation?

 

It seems from my own senses that the engine is extremely lean when it shuts down. When i try to restart... it will try to start but wont. Engine will start to stumble for 5 seconds or so then shuts down. No resart till completely cooled back down.

 

Engine will not run long enough to drive on the highway. Just long enough to move it from my shop.

 

No codes other than the o2 heater? Nothing in pending? Is it possible for you to take a snapshot of the PID data as the car is dying?

I'm going to suggest something on a fluke. Check your idle air control, at idle there should be minimal port vacuum from where it draws air immediately before the butterfly. Just a thought.

 

Ive got a new obd scan tool ordered. Should be here friday. The only code is p1300. From my old scan tool.

 

Bro, that is an ignitor code, not a o2 heater code. What model is your truck?

 

P1300 and the o2 code what should i should have sayed.

 

Well the p1300 is what is shutting down the engine. A non-functional coil or ignitor will cause a misfire condition by sending unburnt fuel through the catalytic. The main priority of the ECU is fuel control and to protect the catalytic.

You may end up just replacing the #1 coil when all is done. Though first check all the leads for it, insulation, use a multimeter between the plug to its corresponding ground and source on the Ecu. When the engine is warm you want to ensure these connections are good, and the ignitor is getting source voltage. If you have a known good part you can just swap it out and see what happens, otherwise do the diagnostic strategy I said above.

 

This is getting a little queer.

 

Lmao jajajaja