Hello new to the group I recently just purchased a 04 that is having a hard time starting and staying running supposedly the engine is rebuilt so far I have of course deflooded. changed the plugs. wires and BHR coils. new crank shaft position sensor and still the same thing I do have a new fuel pump and upstream O2 on the way but is there anybody that has ran into a problem like this before with a motor swap? Like I said I did not do the swap myself so any pointers would be greatly appreciated another key factor is that it will start once cold but as soon as it warms up it will not want to re-fire and if I get it to stay running about five minutes and it’ll kill it on its own. Coolant temp sensor? Or wideband I’m thinking

When I pulled plugs to deflood the right leading was already burnt looking and I’d only ran once or twice since new. Motor does have a tap that comes low rpm but seems to level out at 3k rpm

minimal throttle response


the car is also stuck in open loop fuel

 

No codes at all

 

Standard place to start is a compression test. Cold start and warm problems are often low compression.

Other than that check spark... use a HEI type coil tester. Maybe check that the ESS has been reset as well... common thing to forget and if it isn't done it will struggle to idle.

The usual fuel spark compression trio will usually find your.problem

 

Is that the 20 stomp and pull the room fuse?

 

When it is running what are your fuel trims saying. If they are staying at 0 and it's stuck in the loop then it's the upstream o2 sensor.

 

yes the 20 stomp resets the ess. as stated tho hot starts are a sign of low compression so i would start there

 

open loop yes. Replace wb and fired right up. Quiet for about 5 min. Then died. And wouldn’t hot start. Showing signs of a weak starter. Am changing this morning 🤙

 

A weak starter wouldn't make it die. Did you watch the fuel trims after changing the WB.

 

it fired up and ran for about 5 min. Sputtered around the block but it did not record any FF data. Did get a new code. P2259 sai “b” circuit low. It was previously showing open loop fuel

 

If it's not reading and stft or ltft then it's the WB o2 sensor. If that is bad or a cheap sensor then it will start in closed loop run until warm and shut off when it tries to go into open loop. And it won't start again until it's completely cooled off.

 

that’s exactly what it’s doing. Ordered a new one

 

It should start in open loop and then go into closed loop when it warms up. Not the other way around. Usually it will run in either.... just a bit richer in open loop

It will restart in open loop again but transition to closed loop faster when already warm

It should run without dieing and being difficult to restart without an O2 sensor at all, so I'm not so sure that a new sensor will solve your problem.

I would still want a compression check at some point..

 

I thought the same thing. But when I had my batt out for so long it reset everything including fuel trims. So when I put everything back together it had no trims and couldn't learn how to idle because the WB wasn't giving any info. And there was none stored to idle off of in closed loop.

 

If the WB was giving you strange readings that would make sense... as soon as it tried to go into closed loop it would try and make whatever the WB was doing make sense and trim it accordingly. Usually WB's die and stop working... that would just leave the trims at 0 and it should still run unless you had a leak or something that needed bigger trims

 

yes absolutely will compression test regardless just to know what I actually got stuck with lol.

I did discover a leak on the prim/sec fuel rail. So after having the uim off and on and off and on I managed to get everything sealed up. Went to fire and it will start almost right away and then die. I may have miswired the primaries? I’m going to dive back in it here in a few. Just ran out of time last night.

 

I’m getting can errors now random and when I log I’m getting fuel system at a status 4 or open loop due to load or fuel cut.