Hey guys. I’ve owned a 40 and a 100 for a while now and recently picked up my first 80. It was a little bit of a basket case mechanically, but the body and interior are clean for a 320,000 mile truck. Truck is a ‘94, unlocked, cloth, ABS, full float rear.
The original 1fz to the truck had already blown 1 head gasket and I was told that the current one was blown (which makes #2). The guy I bought it from had sourced a 150k mile 1fz out of a ‘97 to swap in. He chose this route due to high mileage on the current engine and its current issues. Soon after getting the replacement engine, he decided it was more than he could take on and that’s where I came in. There’s a sucker born every day. I picked it up cheap and knew I was capable of the swap.
Fast forward from August until now. The donor engine is in. I did a host of PM stuff to it while it was out. Both oil pans resealed and EGR completely removed and blocked off. I tracked down some service history on the donor and it had recently had the oil pump o-ring and crank seal done. The truck it was in was wrecked and totaled but had been dealer maintained for its 150k life.
Im trying not to ramble too much but I want to use this thread to diagnose my current issue as well as document what’s already been replaced.
When I start the truck up, it goes into high idle warm up like normal and runs fine there. When the RPMs drop to normal idle (~650), it starts to stumble and the RPMs continue to drop until it tries to die. I can then bump the pedal and it’ll shoot back up to high idle before settling back to normal idle and trying to die again. I go through this sequence a few times as the truck warms up and it’ll eventually hold 650 or so RPMs but there’s still a noticeable stumble. You can see it on the tach and hear it at the tailpipe. Shift into gear and it’ll try to die. I can keep it running by mashing the pedal and it’ll eventually take off. Driving down the road it seems to run and shift out fine. Come to a stop sign and the stumble is back.
Things I’ve done. Some of which were done before first start up of donor prior to my knowledge of this issue:
All new fluids
New plugs
New cap, rotor
Dizzy o ring
All vacuum lines replaced
New PCV valve, grommet, hose
EGR blocked at head and intake
New intake tube
Used AFM/Mass air flow sensor. I tried to clean the original and broke the wires trying to remove the plug.
IAC valve cleaned and throttle body cleaned.
New TB gasket
New fuel filter
I inspected the wiring at the EGR and rewrapped it while I had everything out. Wires looked fine. I have run a thermometer across all the exhaust manifold tubes while idling and they all read pretty much the same temp. So I don’t think it’s a stuck injector. I was of the belief that this was a smooth running donor so I think it’s something on the truck side of things. I haven’t checked fuel pressure and I have no idea what the history of the fuel pump is.
I know this is a long post. Hopefully some of y’all will take the time to read it and provide feedback. Thanks
The original 1fz to the truck had already blown 1 head gasket and I was told that the current one was blown (which makes #2). The guy I bought it from had sourced a 150k mile 1fz out of a ‘97 to swap in. He chose this route due to high mileage on the current engine and its current issues. Soon after getting the replacement engine, he decided it was more than he could take on and that’s where I came in. There’s a sucker born every day. I picked it up cheap and knew I was capable of the swap.
Fast forward from August until now. The donor engine is in. I did a host of PM stuff to it while it was out. Both oil pans resealed and EGR completely removed and blocked off. I tracked down some service history on the donor and it had recently had the oil pump o-ring and crank seal done. The truck it was in was wrecked and totaled but had been dealer maintained for its 150k life.
Im trying not to ramble too much but I want to use this thread to diagnose my current issue as well as document what’s already been replaced.
When I start the truck up, it goes into high idle warm up like normal and runs fine there. When the RPMs drop to normal idle (~650), it starts to stumble and the RPMs continue to drop until it tries to die. I can then bump the pedal and it’ll shoot back up to high idle before settling back to normal idle and trying to die again. I go through this sequence a few times as the truck warms up and it’ll eventually hold 650 or so RPMs but there’s still a noticeable stumble. You can see it on the tach and hear it at the tailpipe. Shift into gear and it’ll try to die. I can keep it running by mashing the pedal and it’ll eventually take off. Driving down the road it seems to run and shift out fine. Come to a stop sign and the stumble is back.
Things I’ve done. Some of which were done before first start up of donor prior to my knowledge of this issue:
All new fluids
New plugs
New cap, rotor
Dizzy o ring
All vacuum lines replaced
New PCV valve, grommet, hose
EGR blocked at head and intake
New intake tube
Used AFM/Mass air flow sensor. I tried to clean the original and broke the wires trying to remove the plug.
IAC valve cleaned and throttle body cleaned.
New TB gasket
New fuel filter
I inspected the wiring at the EGR and rewrapped it while I had everything out. Wires looked fine. I have run a thermometer across all the exhaust manifold tubes while idling and they all read pretty much the same temp. So I don’t think it’s a stuck injector. I was of the belief that this was a smooth running donor so I think it’s something on the truck side of things. I haven’t checked fuel pressure and I have no idea what the history of the fuel pump is.
I know this is a long post. Hopefully some of y’all will take the time to read it and provide feedback. Thanks
