88 Bronco II 2.9L Not working right

[rpstevens]

I have a 1988 Bronco II with 2.9L engine and A4LD transmission. Brief history: Engine was running fine and one day while driving the flywheel shattered. I replaced the flywheel, spacer and torque convertor. The catalytic convertor went out, blew the passenger side exhaust manifold doughnut and melted the wires for the O2 sensor. Replaced the parts. Engine would run in neutral, but when placed into gear the engine died. Verified the computer codes and determined the fuel pressure was not correct. Replaced both fuel filters, and rebuilt both fuel pumps.

Current problem - engine still runs but rpms will not go higher than 1500 unless we play with air intake. Playing with the air intake the engine will rev up to 3500 rpms, then the engine gets extremely warm and the radiator boils over. Water pump is OK as is the thermostat. Engine still dies when in gear and the computer does not display any error codes.

Does anyone have any suggestions on how to diagnose or fix this? None of the mechanics I have talked to know what the issue is. I have been told it may be cracked heads, but it does not show the usual signs of cracked heads.

 

[IMenriched]

I have a 1988 Bronco II with 2.9L engine and A4LD transmission. Brief history: Engine was running fine and one day while driving the flywheel shattered. I replaced the flywheel, spacer and torque convertor. The catalytic convertor went out, blew the passenger side exhaust manifold doughnut and melted the wires for the O2 sensor. Replaced the parts. Engine would run in neutral, but when placed into gear the engine died. Verified the computer codes and determined the fuel pressure was not correct. Replaced both fuel filters, and rebuilt both fuel pumps.

Current problem - engine still runs but rpms will not go higher than 1500 unless we play with air intake. Playing with the air intake the engine will rev up to 3500 rpms, then the engine gets extremely warm and the radiator boils over. Water pump is OK as is the thermostat. Engine still dies when in gear and the computer does not display any error codes.

Does anyone have any suggestions on how to diagnose or fix this? None of the mechanics I have talked to know what the issue is. I have been told it may be cracked heads, but it does not show the usual signs of cracked heads.

A guess is that you're still missing a wire or ground after the flywheel took a leave of absence.

but easily boiling over does hint of cracked heads.
when you're say that you "play with the intake"...what is going on ,or what are you doing, so that you can get more RPM's??? just to be clear.

to help determine for cracked head/s, there is a die that you can put into the radiator and see where it coming out.

also another way is, on a cold start...remove radiator cap, and as the t-state opens watch for bubbles in the radiator neck...if you see a steady stream of bubbles....odds are excellent that there is a head cracked or head gasket problem.

 

[rpstevens]

A guess is that you're still missing a wire or ground after the flywheel took a leave of absence.

All the wires are connected, checked it front-to-back 4 times.

when you're say that you "play with the intake"...what is going on ,or what are you doing, so that you can get more RPM's??? just to be clear.

I place my hand over the air inlet and let off quickly, sfter doing that several times then the rps will start to increase.

to help determine for cracked head/s, there is a die that you can put into the radiator and see where it coming out.

did that, couldn't find any leaks

also another way is, on a cold start...remove radiator cap, and as the t-state opens watch for bubbles in the radiator neck...if you see a steady stream of bubbles....odds are excellent that there is a head cracked or head gasket problem.

tried that, did not see any bubbles coolant appears to flow smoothly. The inlet hose to the thermostat gets extremely hard as if it is building up some backpressure which is why I checked the thermostat in the first place.

 

[IMenriched]

well are you able to get the codes??

has a compression check been done??

can you pull the "spout" plug?? does it run better without it?

 

[rpstevens]

well are you able to get the codes??

I had codes when the fuel pressure was low, however since I fixed that problem there have been no codes.

has a compression check been done??

Yes, all of the cylinders were within 1-2 psi of each other and were all within the expected range, if I remember they were between 135-142 psi

can you pull the "spout" plug?? does it run better without it?

not sure what the spout plug is, is it the connector going to the distributor? if so, no I have not disconnected it.

 

[IMenriched]

not sure what the spout plug is, is it the connector going to the distributor? if so, no I have not disconnected it.

Ok, the spout plug is a small ,light or white colored plug. Usually on the passenger side of the intake manifold. Thinking it should be going to the TFI wires (aka ignition module on back side of the distributor housing)??
(the Spout), It plugs into the wire harness to complete a connection for the ecm to take over and automatically adjust timing from the feedback of the various engine sensors. (MAP, 02, TPS, CTS, etc...)

When NOT plugged in and running, it puts the ECM into a constant mode, meaning timing , rpm , & so on are at presets. Removing this plug is how base timing is set. (Base timing which is 10deg TDC).

considering that it dies when tiring to shift....Have all vacuum lines been accounted for and are good??

not to beat a this to hard, but there should be ground wire on the head or block, and the cab to the chassie or exhaust, these can be easily missed, sorry had to ask.

 

[rpstevens]

considering that it dies when tiring to shift....Have all vacuum lines been accounted for and are good??

Yes the lines have been accounted for and are in working order, no leaks or cracks.

not to beat a this to hard, but there should be ground wire on the head or block, and the cab to the chassie or exhaust, these can be easily missed, sorry had to ask.

I have experienced the ground wirew issue before and made sure they were all in place, even added a ground wire to the front of the starter when I replaced the starter a couple of months ago.

Short of removing the engine and transmission, I have gone over the vehicle end-to-end without success. My brother has suggested the computer may be out or going out, is there a way to test?