4.0 ohv performance rebuild

I recently hrydrolocked my motor(4.0 ohv) and believe I bent a rod because the engine won't turn over by the crank with the plugs removed. So I figured it would be a good opportunity to do a full overhaul on my 300k+ mile motor. And while I'm in there, may as well go all out! So my plan from reading posts from you guys, is as follows: my 95tm block bored as little as possible, comp 422 cam, my 95tm heads checked and milled for 988 springs by a shop, and mildly p&p by yours truly, along with the lower intake, 91tm pistons to up the compression, New crank, bearings, all seals and all gaskets. And of course a snorkel to prevent this happening again. I have a few questions that I need help with though. I have read that the 91tm pistons are heavier than mine. Do I need to get the corresponding year crankshaft to properly balance the engine? Will I immediately need a tune before I can drive it? And are there any other issues that I will run into? Its a 96 with obd2. And how long before I can rag on it again? I love my offloading.Thank you for your help and I'm sure i will have more questions as I go along.

 

[Naasau]

Bump.

I have no idea but I am interested in the answers that may be provided. I'm in a somewhat similar situation due to a rollover accident. Only I'm combo-ing with a body swap from donor.

 

[Sebastian Vance]

So almost 8 months to the day we got her running again. I let her sit neglected for a long time then decided to knock it out. We started Thanksgiving weekend and it ran December 3rd at 1:30a.m.

 

[Sebastian Vance]

So we got it to run and drive, just not very well yet. Modifications are: 90tm block and pistons with 98tm heads, heads polished and exhaust ports slightly opened up, 422 cam, EGR delete, no cat just a glasspack muffler. I can't remember all the vacuum stuff, I only have the brake booster and the fuel rail thingy hooked to vacuum. It idled on its own one time out of like 5 runs. There's a clutch problem so I only drove it like a block, but it bogged down and almost stalled. Haven't checked codes, kinda scared lol

 

[Sebastian Vance]

Anyone know what all controls the idle?

 

[Turdle]

PCM and IAC control idle, provided the inputs from all the sensors are corerct and the PCM has entered closed loop.

More important question that needs answered, what codes did you pull? With all the mods this would be the place to start. I wonder if the stock PCM can deal with the cam. If you have not deleted the egr from the pcm control ( illegal by the way) this might be an problem.

My suggestion would be to pull the codes, then disconnect the battery to clear them while you reconnect the egr. Seriously, the egr is not going to take any performance from you and will just cause headaches while trying to eliminate it.

 

[Sebastian Vance]

Yes I know the EGR is helpful and useful, but it wasn't functioning properly prior, and the pipe was damaged on removal. And my intake was really gross. This will be an off-road vehicle and seldom see street use. I will pull codes this weekend to see and let you know, I know that the EGR doesn't function at idle, so I thought it would idle fine without it. I have seen people on here report that the pcm will adjust to the 422, but maybe it has some learning to do from open loop diving?

 

[Sebastian Vance]

Or closed loop whichever is when it learns stuff. Will the pcm save the new information once it learns or will it reset with every disconnection of the battery? I would like to avoid a tune for right now at least but it is eec-v so it wouldn't be too bad

 

[Sebastian Vance]

So it drives fine, sometimes idles decently, but mostly rough idle and won't stay running without a little throttle, and dies when I push the clutch. Codes for oxygen sensor heaters

 

[Sebastian Vance]

Well an update if anybody cares, it now runs and drives very well. The maf sensor and clutch master cylinder had both gone bad. Idles pretty decent, low and lopey. Still needs a few little things but runs great

 

[Sebastian Vance]

Ive got a couple pictures from the build. Honed and gasket surface cleaned up. I'd never honed a cylinder before and man it was a pain. Next time I'll just get it bored

 

[Sebastian Vance]

Pistons installed

 

[Sebastian Vance]

Pistons installed

 

[Sebastian Vance]

Buttoned up