I started my 3.4L the other day and immediatly shut it off because there were several things I still needed to do. Top off the coolent solder a couple wires in the harness etc....

So, here is the problem. I can start the engine and it will run for a few seconds maybe 5 almost sounds like its starting to idel right and then it just shuts off. It dosent seem to be ruinning on 6 cyl. Sounds more like 4 and it runs really rough. It does run though. Its not a misfire.

Keep in mind I could have multiple problems going on at the same time since this is a new swap. The plugs will get wet with fuel if I continue to crank it. I have to turn the key to the off or acc position or it wont start again no mater how much I crank it.

Here is what I have checked, am I missing something?

Coils OK within spec
plug wires tried two sets
brand new plugs (did the same exact thing with the old plugs)
Ignitor hooked to the correct coils
all grounds seem to be fine including the sensor ground
fuel system is pumping till well after the motor dies
If I step on the gas it dies even quicker (seems like a fuel problem but its got plenty of fuel)
Brand new MAF (starts and dies with or withought the MAF)
voltage checks out at the ECU +B and BATT pins
ignitors seems to be pulsing the packs correctly but my meeter cant read that short of a pulse

I know there isnt an issue with the nutal start wire because its starts , right?
seems like its running on only 4 cyl but I know I have the wires right I checked like 8 times.
What else am I overlooking?
Ive been so close for two days now

ANY help would be really appricated.

 

When I put my engine in it did the same thing. I resolved the issue by checking the distributor. Make sure your engine is at top dead center and put the dist to cylinder 1.

 

3.4's dont got distrubutors. Im confused?

 

Oops. Mine is a 3.0.

 

Nope its distributor less. It really is getting to the point where Im willing to buy another ECU just to see if thats what is messed up. Its not running long enough to set any usefull trouble codes either so im pretty much stuck.

 

Well like I said I have a 3.0 in both my runner and my truck. My truck is in the shop as we speak getting a new ECU. It did the same thing too. It wouldn't start. Then it would start. The guys at the shop had it for two days before they decided to replace that. So give it a try, you can always take it back if it doesn't work.

 

Sounds like "unsniffed" air getting into the intake track. Have you checked the entire intake track from the MAFS to the TB?

 

when trying to start the engine do you have the intake tube hooked up to the maf?

 

Does exactly the same thing regardless of weather the MAF is hooked up or not, attached to the intake or not. No matter what I do its starts and dies EXACTLY the same. My first thought was the MAF too, thats why I messed around with it. Its a brand new sensor though

No leaks to speak of in the intake tract. It will still get the plugs all wet even if I remove the sensor from the pipe so that no flow is going across it, so somthing else is going on.

 

did you reset the ecu?

 

Could the IGF signal not be getting back to the ECU? How can I check that? Ummm reset the ECU?

I dissconnected the battery many times if thats what your asking.

If the ECU goies into protection mode all you have to do is turn the key off and back on right? that would explain why it dosent start unless I turn the key off.

 

Another couple of things. I checked the timing belt and all is well, so it hasnt jumped timing. Base timing should all be ok.

 

Best tool I have found for this is a "Logic Probe". Which is like a intelligent test light. It will display different lights if its detected a ground, power source, and small alternating currents (AC).

 

Two things:

1) Checked Compression?

2) Unplug one coil at a time. Which is the effected cylinders? (Fires 2 cylinders at same time)

 

The symptom sounds like the ECU's not seeing airflow, which of course would point to the MAF. Given that you can't change the symptoms by disconnecting the MAF, then it kinda' sounds like it _is_ the MAF, or the associated wiring. I know that if I pull the cable on my MAF, I end up with the same symptoms you're having.

The only other thing I can think of is an echo of what Christian said - there's a leak in the intake path. What about the TB gasket? I know that I've put a couple on "wrong" and had pretty similar symptoms. The intake path is pretty sensitive...

 

Do you have the same year ECU as you do motor?
Do you have the OBD system functional as well?

OBD would be the best place to look and see what all the sensors are seeing and hopefully pinpoint the problem much quicker.

 

Thanks guys you seem to have lead me in the right direction. I traced my MAF wires out to the plug at the ECU and guess what, they are in a different location than it shows in the FSM? The wire harness IS from a 96 4runner so I have no idea why the pins would be moved around. The ECU is from a 98 so im gussing that some of the very early models of 96 were not compatible. Thanks again toyota :/

Working on the problem now

 

If That Doesnt Work.. Maybe Try Cleaning The Throttle Body?