Jeep Strokers

Hey all, Stroker noobie here.

I have a Golen 4.6 stroker in my WJ, its been running great with pretty much no issues for about 18 months now. This past weekend I finally got around to upgrading from the stock TB to a 62 mm Fastman throttle body. All went smoothly with the install and everything is great durign normal daily driving...However, if I mash on the gas in the higher revs i begin to get some misfires around 40 mph and nearing 4000+ rpms. CEL light came on with 2 cyclinder misfire errors and the multiple misfire error. I have tried 2 hard accelerating trial runs since getting this error and was able to repeat the misfires. On the last time the misfires actually lingered for awhile, I actually had to pull over and stop and restart the motor. Once again all is fine for DD.

So all i did was go from stock to a 62mm throttle body. Reset the computer by removing the positive batt cable from the vehicle for the entire install. Did some driving around in a parking lot before heading out on the roads.

I have a Golen stroker, 24 lb injectors, CAI, and this 62mm Fastman TB, stock 2000 wj computer.

Chad at Golen and Fastman have both hinted at this maybe being a lean fuel issue or a computer issue. Any ideas? Did I reset the computer correctly? Do I need to look into tuners at this point?

I'm thinking lean issue too. Do you have a wideband gauge? Exactly what is the part number on the injectors? Have you checked your fuel pressure? Any audible pinging?

You can go and put the stock TB back on and see if that fixes the issue.

What would that do? Its not a problem with the throttle body as it only happens at WOT. If there was an idle issue I would consider the throttle body. Other options could me the TPS or MAP sensor.

SilverXJ wrote:What would that do? Its not a problem with the throttle body as it only happens at WOT.

Could be that the extra airflow from the larger TB is causing the engine to run lean at 4000+rpm under WOT.

Thanks guys!

No audible pings.

I thought i would be able to get fuel pressure measurements from the ecu via the Torque app but my data came back blank. I'll try again this weekend before I revert back to the stock TB.

No fuel pressure measurements on the 4.0L unless the last TJs might have it. You will have to get a fuel pressure gauge with a long hose. If your pressure is dropping off you have a problem with the fuel pump, which is a problem w/ or w/o the throttle body.

Cheromaniac wrote:Could be that the extra airflow from the larger TB is causing the engine to run lean at 4000+rpm under WOT.

That doesn't make it a problem with the throttle body.

Right, but what would change with the fuel pump after installing a TB if the stock TB worked just fine at WOT, not up to snuff?

Yes. Perhaps that bit of extra air just pushed the pump over the edge. If fuel pressure checks out when the problem is happening its not the fuel pump. PCM may just not be giving enough fuel.

Also, check the TPS and MAP sensor since they were moved. And make sure that little elbow under the MAP is good and connected.

Even if it is a lean condition it would have to be supper mean to misfire. If it is a lean condition you most likely have it with the stock throttle body as well, jut you didn't notice it. Yet.

Since you have torque app take a look at the fuel trims, O2 sensor data (when this happens the stock sensor should be showing rich if its correct), TPS and MAP sensor data too.

Yup. Put the stock TB back on this weekend, no problems at all at WOT.

I'm still having trouble getting info out of torque regarding the fuel, has anyone else done this?

I have a 1997 Jeep TJ with a Golen 4.6 Stroker and a BBK throttle body.

After about 800 miles on the engine I began experiencing a rough idle at start up. The idle was bad enough to throw a misfire codes across many of the cylinders.

Additionally, I lose momentary power when I mash hard on the throttle.

On a side note, I bought the fancy valve cover from Golen. When I removed my throttle body to clean it to try and fix the problem, I noticed oil in the intake manifold. Per Chad Golen, that sometimes is caused by his valve cover and suggested I install a check valve in the line between the valve cover and the intake manifold. Since I installed that, the problem had been reduced but still remains.

Based on the above posts, I’m going to look for a stock throttle body and see if replacing the BBK one with stock fixes the issue.

Does anyone have any other ideas or suggestions as what’s causing the random misfire? This seems to be an issue non-stroker TJs face as well. What’s the answer?

Thanks,

Brian

Too many variables to diagnose with not enough info. I doubt it's your throttle body though. I also worry about the oil in the intake. Where is this check valve supposed to go? I had one on my Skyline, but that was boosted.