Starting issue

[4.whoa]

On the aftermarket TB is the set-screw adjuster thingy under the throttle arm. I cranked the engine and turned the screw til it said 1K on the tach.

the stock TB also has a setscrew like that, but it's NOT for idle adjustment.The idle is controlled by the IAC(idle air control) the little round motor on the side of the TB. It's basically a controlled (by the computer)vaccum leak that sets the idle. Was this the start of your starting problems? Doing that not only keps the IAC from doing it's job properly, but it changes the TPS signal a little bit, so that might be your problem right there.

I've never heard about setting idle that high for "break in" before.The cam brake in is what's vital,which does NOT involve idling. Then there's the "seating the rings" which is full throttle from 30-50 mph IIRC & NO throttle back down (without any gear changes) 3-4 x's

Was your header all that was glowing or was anything else, like the cat also glowing?

[FOXxX]

Was this the start of your starting problems? Doing that not only keps the IAC from doing it's job properly, but it changes the TPS signal a little bit, so that might be your problem right there.

I've never heard about setting idle that high for "break in" before.

Was your header all that was glowing or was anything else, like the cat also glowing?

I only wish it was the start of my problems. I've had the starting issue since I first cranked the SOB. Last night I went out and set that screw back down so that the Butterfly was completely closed. I also took off the TB riser because I heard that could mess things up too.

The idle at 1K thing was more of a help with the 500 mile thing and not the cam break-in. This was to keep the motor from idling in such a rich state until the engine was broke in completely.

Also I never noticed the cat get red - I will pay attn tonight when I get home. I know that the passenger side floorboard will cook your feet though. I need to custom some heat shields for the exhaust. I dont have carpet installed due to the rotting floorboard problem the XJ's have.

[SilverXJ]

Yes, that set screw is not for idle adjustment. The FSM specifically states do not touch that set screw. However, Lee @ Hesco recommends checking it and if you need to drill a small hole in the butterfly. IIRC idle should be around 700rpm.

Now, the headers glowing when normal driving is a problem. However it could be a rich problem as well. I.e. unburnt fuel burning in the headers. Which isn't good for the cat either. In normal driving the PCM should be controlling the AFR to 14.7:1. That would be closed loop. When you hit the gas and get the TPS above a certain value (varies between years, iirc earlier years is like 55%) it goes into open loop which is where you will most likely see a rich or lean condition. Which could be normal without adjustment. It will also be in open loop on a cold start, until engine is up to temp.

Also, that set screw needs to be in a certain position, nut just backed out.

Here is a quote from Lee on checking idle:

First thing to check is base idle air.

Do this by putting a playing card over the idle air slot in the top of the throttle body. Engine should idle at 700 to 750 rpm and not stall. If high look for a vacuum leak (most likely the intake manifold bolts).

If engine stalls you need to drill a 3/32 hole in the throttle butterfly just above the shaft. If 3/32 is not enough increase till you have 700 rpm with card over the port.

[YJason]

Not sure about your temp. issues but maybe the IAC is bad on the TB?

[FOXxX]

I took the stock throttle body and measured the angle on the throttle lever where it connects to the TPS and adjusted the new TB to match. Hopefully this would put the TPS back in the original position of stock. Next I took the advise from "Lee, at Hesco" prev. posted and started with the playing card and had to drill a hole up to an 1/8th. Hopefully all of this would keep my computer thinking its as close to stock as it can get.

Pulled a spark plug and noticed the tips were ceramic white - indicator of lean mix. Installed the adj. MAP back into the mix and started adjusting the voltage from stock in .1 increments. Where did that get me? Well it reduced the brightness of my headers glowing at idle significantly. Stock MAP is at 4.16V and I ended up at 4.85V before I had to call it quits - turned into a garage party, I live on base, and they dont tolerate beer and driving. I will start back up today and see where it all ends up. Maybe I'll pick up a Air/ Fuel meter today just to help. I'll keep you guys updated.

[FOXxX]

So the results are in - sort of. I purchased a narrowband stoich meter(I hated to do so for only this reason) and I do understand that the narrowband is more of an average - well sort of.I learned that the meter reads exactly what is shown from the O2 sensor in volts and as soon as it gets the reading it displays that reading and since it see's so many readings per second its value jumps a lot. Well at least mine did. If I could slow the sample rate the meter see's then I may be able to see a more stable reading. Now that I understand what it is doing I can see what it is doing.

When I have the adjustable MAP hooked up the reading seems more unstable. It is almost as if the PCM is very confused. Remember the setting was last at 4.85V on the adj. MAP - So idling and easy riding seemed to average more on the stoich/rich side occasionally dropping to the real lean side. I tried to time this to see if it was at a specific cylinder fire but it was at random. I put the volt meter on the O2 line to read exactly what was going on. When the engine was on the richer side volts were at or about .700V. When it dropped to the lean side it would read .200V. I also noticed that it corresponded to the engine surging while idling. Seemed like the PCM would see this .700V for too long and cut the fuel for a sec and then read the .200V and give it more fuel. On the highway at accel and cruise speeds the stoich meter read more on the stoich/rich side. WOT would register on the rich side but when let up it would settle back in at the stoich/rich. All the while the vehicle never maintaining a good hwy speed because it lacked power - indicate to me that it is running too rich.
Without the adj MAP hooked up vehicle acted identicle at idle and easy riding (<30 MPH, easy accel). On the road at cruising same readings on the meter except the motor maintained a hwy cruising speed. The only time the meter ever seemed to read a lean reading is during decel and letting up of the gas which would almost make sense because im not giving it gas.
Here is my concern at this point - why does my header glow at idle and why do my spark plugs look fried. Could my O2 sensor be bad and sending bad readings to my PCM? Everything else seems to be normal!

[SilverXJ]

The only way you can get a good reading from the spark plugs is to do a WOT run (pedal down). Then shut it off when you let off the pedal. Then check the plugs. The tip of the porcelain won't tell you much based especially with low miles on the plugs. You have to look at the base ring (ring right after last thread) to get your AFR mixture reading. Again it needs to be done after WOT. Cruising around the engine runs lean any how at 14.7:1 or so. Then gain, I am really not sure reading plugs works that well on a fuel injected engine. See here: http://www.dragstuff.com/techarticles/h ... plugs.html and google "reading spark plugs". If you find a site that has an image similar to the ones you see in a Chilton or Haynes Manual, don't even bother with it.

The decel lean you see on the gauge is correct. It will go very lean when you let off the gas, around 19:1. You mentioned surging at idle. I don't recall if you did before but the only time I experienced that was when I had injectors that were too large.

As for the headers glowing. Could bee too rich could be too lean.... or the timing could be off. Did you degree the cam in?

[FOXxX]

Sounds like everything on my end is running fine then - I still have the original injectors and I may throw them back in to give them a try and see if everything settles down. Like I said normal driving showed on the richer side even without the adj. MAP. glowing headers could be the result of rich mix too - all caused by too large of an injector (the pieces of the puzzle are fitting together nicely). As far as the spark plugs - tips of them are the white looking, whereas the bottom around the rings were black. If that is the place to check then all together the thing is just running too rich. I will put the old injectors back in and give it a try.

Next question - is there an inbetween injector that I may set my sights on?

Thanks for all the replies so far!

[SilverXJ]

Everything I have found about your injectors says they are 24 lbs/hour. If you had a 97+ I could recommend an injector for you, but you don't. I still think there is something else wrong becaus even with a slightly large injector the PCM should be able to dial out enough fuel or add enough to stop the headers from glowing. How many miles do you have after the last computer disconnect? And what about degreeing the cam in?

You also mentioned a power loss, could you give me more details on that?

[FOXxX]

Well I really haven't disconnected anything since installing the motor in the beginning - I disconnected the batery when I installed the E fan about 200 miles ago. Other than that, I wouldn't even know how to diisconnect or reset the PCM.

I didnt degree the cam in - the machine shop built my engine and degreed it in for me. When you say degree the cam - my eyes glaze over and I stare with a blank face.

Power loss was when I had the adj. MAP in the loop and cruising at hwy speeds - it didn't have the sustaining power nor once I was up to speed I dont get much more response from the engine after that. Without the adj. MAP I can sustain speeds but power to move fast after getting to say about 65 - 70, well there is very little. However I have larger tires - 33's - so I just thought it was because of the tires. If there is supposed to be a significant difference between the 4.0 and this 4.6 - I have yet to feel it.

[SilverXJ]

From everything you describe it sounds like you have something bad going on. Maybe a stuck open injector, maybe a few. Maybe the cam isn't degreed in properly. Of maybe its something as simple as a bad O2 sensor.

I would swap out the injectors with your stock injectors and see what happens. And reset the PCM after you get them in by disconnecting the battery cables and touching the cables to each other for like 30 seconds. Just don't do any long full throttle runs with the stock injectors.

[FOXxX]

Well I thought about maybe stuck open injectors before and pulled the rail, left the injectors in place and applied power to the pump. No leaks. I will question the degree the cam is in but surely an experienced egine builder doesn't forget that important step! As far as resetting the PCM - I thought about it and I've never really reset anything since swapping out anything that may require a computer reboot - silly me. I just read up on the toothpick thing so I am going to go through and make sure all of the small stuff is taken care of. Any good way to check the intake for a vac leak? If the spark plugs ran on such a rich mixture could they have fouled out? I replaced the CPS on the dizzy but not the dizzy itself - is that bad? Could the crank sensor give me these fits?

Anyone want to buy a 4.6 stroker? - sigh

[jbxx]

A good way to look for vacuum leaks is with a propane torch.
Not lit of course but opened.
Please be carefull doing this.
But as you move the head around all places that would be a potential leak,
if you come to a leak the engine speed will change.
Also obvoiusly do this outside. With a fire extinguisher handy.

[SilverXJ]

I will question the degree the cam is in but surely an experienced egine builder doesn't forget that important step!

Who knows. It maybe something he doesn't do unless asked

As far as resetting the PCM - I thought about it and I've never really reset anything since swapping out anything that may require a computer reboot - silly me.

It will relearn on its own, but I don't know how long it would take. And it will relearn on its own after a reset.

If the spark plugs ran on such a rich mixture could they have fouled out?

You would see ifthey are carbon fouled or not.

I replaced the CPS on the dizzy but not the dizzy itself - is that bad?

Not bad unless the distributor is damaged in some way. The CPS is the Cranks sensor on the bellhousing. Cam sensor is usually abbreviated CKP.

Could the crank sensor give me these fits?

I don't think so. But maybe your coil could be on its way out and not giving it enough spark.

Anyone want to buy a 4.6 stroker? - sigh

Not every major modification is a walk in the park.

[FOXxX]

Well I tried to do the toothpick thing but I do not have a hole to line the thing up with so I will scratch that one off the list. I swapped out the 24lb to the stock injectors. stoich meter is still swinging back and forth during driving and idle. You may be correct in the coil - I have the accel performance coil that I bought a month ago but never installed it in order to troubleshoot other issues. I think it is time to see what this thing can do for me. The coil is just about the only part on the engine that is not new. I bought the injectors from someone and not 100% they are ok so im going to shop for more. More to come.