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Old 06-10-2010, 10:34 AM   #1
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01 - rough idle/hard start and now no start

Have an 01 wrangler 4.0L with 80K miles that had been suffering from a hard start and rough initial idle problem for a bit now.

I was sort of suspecting the fuel pump/check valve for the hard start, but had been turning ignition on for a few seconds before cranking it and havent noticed that problem as of late.

The rough idle would normallly go away once warmed up or if you goosed the throttle.

I replaced plugs and the air filter last weekend and the rough idle problem happened on the first start after the new plugs and then hasnt happened for the last week. Now this morning, it wont fire at all.


No CEL or codes.

It cranks as normal.

Battery terminals are corroded a bit though had replaced the ends a while back due to loose fitting. Will clean them off properly tonight as I didnt have time this morning.

It has fuel pressure at the rail though not sure of exact measurement. Would guess about what it should be based on how hard it squirted out when I hit the shrader valve.

Old plugs didnt show any sign of running rich or with oil and engine does not use much oil. They were corroded though with the elements being the green/copper color. So might show signs of running either correct fuel mix or to the lean side.

Pulled a new plug today and looks normal with proper gap still.


So I'm suspecting either crank position or coil or maybe fuel pump (picking up a fuel pressure gage tonight to test exact pressure). Didnt have a helper this morning so I couldnt check if the vavles were clicking on and off as it cranked.

Normally my next step (aside from feeling for the clicking of the valves) would be to check for spark at the plug, but this thing has this solid direct fire rail instead of normal wires, so how do I go about checking for spark. Its damn near impossible to move that solid rail around to get a plug in it and grounded to the block while still able to see the spark.

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Old 06-10-2010, 10:37 AM   #2
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clean the battery contacts, then put those little felt dodads on them, and then we shall see.

that corrosion can cause both of your problems.

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Old 06-10-2010, 10:38 AM   #3
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Quote:
Originally Posted by atuel View Post
Have an 01 wrangler 4.0L with 80K miles that had been suffering from a hard start and rough initial idle problem for a bit now.

I was sort of suspecting the fuel pump/check valve for the hard start, but had been turning ignition on for a few seconds before cranking it and havent noticed that problem as of late.

The rough idle would normallly go away once warmed up or if you goosed the throttle.

I replaced plugs and the air filter last weekend and the rough idle problem happened on the first start after the new plugs and then hasnt happened for the last week. Now this morning, it wont fire at all.

I did this one time. Mashed a plug together when I was putting it back in.. Took them all out and the last one had no spacing. Check the plugs one by one and make sure the wires are on good.
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Old 06-10-2010, 10:41 AM   #4
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seems to be alot of threads about the same thing or something similar.

for example: this link.
http://www.wranglerforum.com/f5/01-s...sue-52034.html

Maybe Idle Air Control?

Has anyone ever had to replace their "rail coils" due to problems?
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Old 06-10-2010, 11:28 AM   #5
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check cam position sensor
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Old 06-10-2010, 12:30 PM   #6
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I tried cleaning my IAC a while back... didnt really help or change anything. Never tried replacing it but this was the thread I saw a while back about it:

IAC question - JeepForum.com



The cam position sensor was in the back of my mind, though hoping thats not it as heard its a pain to change.


But back to the main question I had... how do you guys check for spark with this solid direct fire rail instead of ignition wires?
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Old 06-10-2010, 12:31 PM   #7
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Did you ever visually inspect the back of each plug?
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Old 06-10-2010, 01:01 PM   #8
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There are some device on the market that can assist for checking that a coil is firing.

such as:
http://www.sjdiscounttools.com/kd2756.html

This is a fake spark plug. you plug it in, attach the clip to a ground spot (no paint!) and have someone turn over the key. If the coil is working, you should see a spark or arc. These work very good with some applications. better in the dark. Make sure it's not near any wiring!


I think these take about 16KV or more to fire.

theres another one that looks the same.

http://www.oreillyauto.com/site/c/de...0221&ppt=00000

It's a lower breakover voltage of about 10KV to 12KV. Best suited for regular engines.
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Old 06-10-2010, 01:10 PM   #9
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Originally Posted by drivebytruckerz View Post
Did you ever visually inspect the back of each plug?

I inspected all the old plugs... other than the corrosion on the element, nothing out of the ordinary. First plug from a running engine I've ever seen corroded like this so found that a bit odd and may indicate its running too lean.

The new plugs are only a week old and since this only happened this morning I didnt have a chance to pull each of them out for inspection. I did pull the #2 cylinder one as I was planning to check for spark, but ran into the problem of how the hell do I do it with the solid ignition rail.

The old plugs may have been part of all of the rough idle problem, but for this failing to start, its hard to believe its the plugs as all 6 would pretty much have to go bad for it not to fire at all. I could see fire and die if some of them were bad, but not a complete failure to fire at all.

For that matter, that probably rules out the coils. I'm used to dealing with a single coil in my classic cars, but this thing has 3 coils on the ignition rail, so again, it should fire at least some unless all 3 went bad at the same time which is probably unlikely.


So that leaves the crank and cam position sensors and possibly the fuel pump for reasons it wont fire. And possibly lack of current from battery terminal corrosion. Maybe a vacuum leak as well? Battery terminal is easy to clean, so I'll do that tonight when I have time. I'll check the exact fuel pressure tonight to rule the pump out but like I said above, from the "redneck" guess I made with letting it squirt fuel all over my hand, it appears to have plenty of pressure.


Anyone have a guide for the cam sensor if it comes to that? Never done that myself and only finding info for the older models that doesnt really apply here to my 01.
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Old 06-10-2010, 01:11 PM   #10
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Originally Posted by PTaylor View Post
There are some device on the market that can assist for checking that a coil is firing.

such as:
K-D Tools 2756 - HEI Ignition Tester

This is a fake spark plug. you plug it in, attach the clip to a ground spot (no paint!) and have someone turn over the key. If the coil is working, you should see a spark or arc. These work very good with some applications. better in the dark. Make sure it's not near any wiring!


I think these take about 16KV or more to fire.

theres another one that looks the same.

KD Tools 2757 - Ignition Tester | O'Reilly Auto Parts

It's a lower breakover voltage of about 10KV to 12KV. Best suited for regular engines.


I guess that would make it a bit easier... but then again, i could just a piece of wire with a clip on each end to do that. I guess thats what I'll have to do since this damn solid rail makes it impossible to set the plug up against the block and see it spark that way.
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Old 06-10-2010, 01:13 PM   #11
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You could stick your finger in each coil of the rail and have someone turn the key over. you'll know quick if it's working or not
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Old 06-10-2010, 01:21 PM   #12
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You could stick your finger in each coil of the rail and have someone turn the key over. you'll know quick if it's working or not

heh... I figured thats what the jeep engineers expected us to do. This solid igition rail is the worst thing I've had to work in in years. I mean whats wrong with plug wires... its tried and tested and been around forever. GM does direct fire with plug wires. I'd imagine its even more expensive to make and assemble, so gotta ask what idiot dreamed up this design and what problem was he actually trying to solve.
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Old 06-10-2010, 01:42 PM   #13
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For testing if a spark or not on the coil rail type system -
Make 6 short plug wires about 6" long without boots. Then just use them to extend long enough to get to the plugs.

If you are using a scope, make those wires longer, about 18". Then after connecting them, bundle them together and wrap a piece of aluminum foil around them at the center. Clip the coil wire probe on the foil or place an HEI adapter against the foil.

Right - all 6 would have to fail.

Check to make sure you have fuel squirting out the Schrader valve during cranking. Just checking it not cranking doesn't tell much.

IF you have no fuel during cranking, and no spark swap the ASD relay with the horn relay to test the relay. Else suspect the crank position sensor on the bellhousing.

Before replacing it, try disconnecting the plug, spray the terminals with electrical cleaner not wd-40!. Put a tad of dielectric grease on the terminals and reconnect.

That connecter - hard to see - hard to reach - back of the engine - wires run down behind the valve cover to the top of the bellhousing. Pull the Red tab out 3/8" (the lock) pull the connector apart.
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Old 06-10-2010, 05:03 PM   #14
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Cleaned my battery and just swapped the relays for the hell of it since I was under there....


Now I get a p0320 code.... no signal from crank sensor. Any possibility that this is just needing to clean the connection on the passenger side?


If not, how the hell do you get to that thing? In through the wheel well?


Its about a billion degrees outside now so cooling off here, but I'll go try to clean the connector with some MAF cleaner later tonight when its cooler.
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Old 06-10-2010, 05:42 PM   #15
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Progress!

You reach the connector from the right side. There's usually enough extra wire on it to pull it out a little to get to it.
Standing on something helps.
Unfortunatly it's a fairly common problem.

I wouldn't use MAF cleaner - use electrical contact cleaner (or even rubbing alcohol) then a dab of dielectric grease.

Sounds like it was the relay too - they are cheap.
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Old 06-10-2010, 06:08 PM   #16
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Progress!

You reach the connector from the right side. There's usually enough extra wire on it to pull it out a little to get to it.
Standing on something helps.
Unfortunatly it's a fairly common problem.

I wouldn't use MAF cleaner - use electrical contact cleaner (or even rubbing alcohol) then a dab of dielectric grease.

Sounds like it was the relay too - they are cheap.

So you go in from the top always? Found this how to guide that looks like hes going in from behind from the wheel well. He doesnt say so specifically, but the picture looks like it if you click on it to blow it up.
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Old 06-10-2010, 07:31 PM   #17
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You might be able to reach it from the wheelwell if your arms were 5 feet long, and you are a contortionist. It's not even close.

Look at the valve cover - at the back by the firewall. Go on the left -drivers- side - feel behind the valve cover, then down to the bellhousing. A thin harness is back there. Follow it up and toward the passenger side - still behind the engine. The black connector is right there. It only has 2 wires in it. You'll need to standing on the passenger side to undo the connector.

The picture you looked at might be for the cam position sensor - something entirely different. THE CRANKSHAFT POSITION SENSOR (CPS) IS AT THE VERY BACK OF THE ENGINE.
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Old 06-10-2010, 08:50 PM   #18
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Well, replaced the crank shaft position sensor and have fire now, but dies with in seconds. Ended up I could easily reach it from below. I couldnt get a wrench in from above, but a socket with a 6" exension worked from below a single click at a time.


Fuel pressure is 45-50psi.


Only code is the same p0320.


Any ideas? The cardboard spacer was on the sensor when I installed it.
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Old 06-10-2010, 09:55 PM   #19
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Gee - I see you follow instructions really well. I just wanted you to disconnect the connector, then re-connect it. Not replace it.

I hope you used one from a Jeep dealer, not a knock-off from China. Discount parts places get them from China - often they don't work right from the beginning.

Clean the codes, disconnect the battery a minute or so - deep cleaning isn't needed.
See if the code comes back, or another one.
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Old 06-10-2010, 10:28 PM   #20
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I skipped saying I cleaned the connector... i tried that first. No effect.

So off to replacing it. Jeep dealer was closed so took a chance at advanced auto. Got a BWD branded one... its made in mexico so not exactly the cheap chinese crap, but maybe not that far off. And hey, its approved by NASCAR performance... . But all jokes aside, replacing it got me some fire... just not the ability to run continually.


So I pulled the plugs and they appear to be sitting in gas, but there appears to be beads of water on the plugs. Its been raining like mad here and there have been news stories about water in the gas at the gas station. We did fill up the night before this happened, so wondering if I picked up some water in the gas. Looked down through the butterfly valve on the intake and its bone dry, so thinking gas as this point Any suggestions on getting this to "dry out" short of drain the system.

I also pulled some connectors under the hood like the TPS and theres water in them. That really concerns me. I have a damaged fender on one side due to guy dropping a tire of his trailer in front of us on the interstate. Wondering if thats letting too much water into the engine compartment. I definitely wouldnt expect to see water in the connections. There also appears to be no dielectric grease in these connections. Does the factory install that?


One other thing I noticed is the throttle cable has some slack in it at rest. Should this be tight at rest or is this normal?
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Old 06-10-2010, 10:30 PM   #21
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I also cleaned the battery including pulling the connections for 15+ minutes while the acid neutralized a few times. The code came back after just the cleaning. I'll go try it again here.
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Old 06-11-2010, 12:54 AM   #22
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Well, got it started with the help of some seafoam and draining a bunch of gas out the fuel rail while pulling the plugs to let the chambers "dry" with the battery cable pulled for a couple hours. New tank of gas with more seafoam and ran it hard for a bit. Seems to be running better than ever now.

Actually seems like it has more power too... ever hear of a crank sensor robbing power? Certainly firing at the wrong time would not be optimal for power or gas mileage which are both things we've not been too happy with.

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