Finally got the 4.7L running! HP Guess and injector?

[CobraMarty]

Didn't say it did. Still need wideband AFR gauge.

[Rinkrat456]

I know how scan tools work. They won't tell you anything about open loop/WOT AFRs.

WOT relies on open loop in GM vehicles, I'm assuming it's the same way with these Jeep PCM's?

At what ECT does closed loop enable on these PCM's?

[Cheromaniac]

1. I thought above we agreed these injectors would be a good choice?

Dino if you were saying 25.7Lb/hr injectors were the recommended choice, these would give us room like you said for a better intake and exhaust which are in this Jeep's future.

There seems to have been a misunderstanding. I was actually recommending the Accel 24lb'ers but before you go swapping out your Chevy injectors (it might not be necessary), let's try to troubleshoot the problem with the engine not going past 3000rpm. I suggest you begin by testing the fuel pump.

[Rinkrat456]

.... let's try to troubleshoot the problem with the engine not going past 3000rpm. I suggest you begin by testing the fuel pump.

Working on this tonight actually. Getting a fuel test gauge has been a bit of a pain. My buddy came over last week with his age-old fuel pressure gauge but the fittings were not correct for the Jeep's fuel rail so I ordered one from Summit Racing. Admittedly I ordered this tester quickly on my phone and did not read any further into the specs other than what Summit provided and when it arrived on my doorstep yesterday, on the back of the package it reads "NOT FOR FUEL INJECTION"....good to 10psi only. Frustrating then I drove last night to the parts store and bought a nice Actron model with a 6ft hose. I'll use it for future projects so it's a decent buy. By the time I got home it was already time to get ready for bed so I'll test this evening after work.

[Rinkrat456]

updates:

fuel pressure is perfect. pump seems ok. got a gauge hooked up to the fuel rail nipple and 49-51psi at idle. gauge needle flutters back and forth +/- 2psi from 50 at idle but once you rev the engine even a little it locks in at 49psi perfectly. went for a short drive after engine warmed up, taped the gauge to the hood. gauge needle doesnt fluctuate at all from 49-50 even at wot. so, pump is fine.

low speed delay seemed to tune itself out. its no longer there from what i can tell.

still having a big issue with a 3000rpm rev limiter. any gear, any speed doesnt matter engine wont rev over 3000. watched the fuel gauge during the 3000rpm cut-out and the gauge needle bounced the most during this limit, dropping to 45 and back up to 50ish cycling very quickly as different cylinders cut out. what causes a 3000rpm limiter to kick in like that?

also still experiencing a drastic loss of power when trying to accelerate onto the highway from 20-70mph. 3rd gear pulls suck. from idle to about 2000 +/- it pulls like a 4.7l stroker should, but from 2000-3000 it flat lines and doesnt accelerate hardly at all. we previously thought this was fuel related but thats out of the picture now. any other things to test?

[yuppiexj]

Have you checked the function of your CAM sensor? the one in the distributor assembly, not the PITA one on the bell-housing.

I had one that got a good splash of water on it, that led to similar/same issues. sputter above ~2200 RPM and no chance of going above 3000 RPM.
It went away after the water dried out. 4 months later it died completely. The rig would start and idle just fine, any more than a touch of throttle and it would spit and sputter.


yours is a 98, mine was a 94. I am unsure if it makes a difference.

[Rinkrat456]

The cam position sensor (and distributor) are from the original 4.0L that I drove into the garage before ripping it out for the 4.7L install. Granted, I didn't get any time behind the wheel of this '98. My wife and I bought it for cheap knowing full well that the engine was "terminally ill" which we didn't care about because we already had a built 4.7L for it. We picked it up from the sellers, drove it onto the trailer, towed it 3hrs home and drove it off the trailer and into the garage. Under the cap, the distributor looks to never have gotten wet or damaged.

The crank position sensor in the bell housing is still the original that we drove in on. It was removed during the engine swap and looked fine upon inspection. Dusty and old, bust intact. No calibration has been done within the PCM...not sure if that's something needing to be addressed. Some GM processes call this a "crank relearn".

[gradon]

I've had a bad Accel coil prevent me from going over 3K. This past week I again tried the MSD coil that failed half-way around the block 2 years ago after installing the new timing set and it worked for 15 minutes then died again right when I was accelerating onto the beltway :p

[Rinkrat456]

Checked spark late last night and it is very weak according to this youtube video:

http://www.youtube.com/watch?v=eNx9YDodgE0

I hardly get a fraction of the "good spark" tests from the plugs I checked. This could be the cause of my low power feel from 2000 on up especially at higher loads, until 3000 limit. Plugs looked fine but they've been through 3 different sets of injectors from lean to rich so those will get changed as well, along with the coil and plug wires. When we replaced the engine, only the plugs were changed.

After the coil, plug wires and plugs are changed I'm hoping the power is restored and 3000 rpm limiter goes away, but assuming the limiter stays what other sensors or ignition related parts cause such a situation?

[Rinkrat456]

Update: Replaced the plugs, wires, cap, rotor and coil. Feels way better. Power seems to be up compared to this morning. Engine runs smoother all the way up to 3000rpm but that limiter still kicks in so I haven't been able to feel the full rev range. I took it out on the highway for a quick spin after replacing the ignition parts and gunned it. Power was great all the way up to 3000rpm where before it wouldn't accelerate worth a damn. Unfortunately spark gets cut, engine sputters like I'm hitting a rev limiter and it won't go any higher. I wanted to force the engine to go a little higher so I got back onto the highway keeping the automatic in 3rd gear and at 50-55mph I dropped it down into 2nd and RPM's skyrocketed to 4000+ but the limiter kicked back in and brought it back down to below 3000. Power felt like crap above 3000 with the limiter bringing it down.

So, what causes the limiter to kick in like that now that ignition parts are all top of the line Napa line?

[gradon]

Maybe the dizzy is off a tooth--pull it out and try re-syncing the CMP underneath.

[Rinkrat456]

Maybe the dizzy is off a tooth--pull it out and try re-syncing the CMP underneath.

How does one check if it's 1 tooth off? or re-sync the cam position sensor?

[wjtom]

Easy way to see if its spark or fuel related.Hook up a timing light and have someone go for a ride with you and watch the light.Doesnt matter which wire its hooked to as you are only looking for a loss of spark.As rpms come up light should go pretty much solid if it flashing and dropping out you have an ignition problem.Nice and simple.

[Jim K in PA]

Any updates? Just read through this and my first thought was cam/crank pos sensors out of sync. My '05 has the later distributorless ignition, but if the cam sensor is out of sync it will throw a code and limit RPM to 3k. No codes are being thrown? Not even a P030X?