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Unread 04-03-2011, 09:11 PM   #16
kc10er
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1991 YJ Wrangler 
 
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great idea! i always seem to take the hard way (aka REPLACE one at a time). I will do that tomorrow. I'll get it up to temp and unplug one at a time. Thanks man, and thanks on compression comment, I was happy even though I wish #2 was a little closer to 130!

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Unread 04-05-2011, 06:40 PM   #17
kc10er
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well, replaced the injector. now it won't even start. Plugs are wet so i know it is getting fuel. Thought i might have fouled a plug so i bought new ones. Gapped to .035. it just cranks and cranks and the exhaust smells like gas when i stick my nose in the pipe so it has to be getting fuel. i have fuel and spark and no bang.

So now i am worse off then i was and out more money. Anyone have any suggestions? If not I am about to sell this POS.
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Unread 04-06-2011, 07:16 PM   #18
kc10er
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UPDATE: Jeep is for sale, fk this thing. Serious offers over $6,000 PM me for a parts list (bunch of new stuff like LED lights, bumpers, winch, tires, woods drive shafts, etc) and parts replaced to date. Jeep will crank, no start.
Pics available for serious buyers. I am done with POS american products, back to sport cars for me.
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Unread 04-06-2011, 09:20 PM   #19
NonRubicon
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Sorry to hear that you've given up. Keep in mind though that you are dealing with a 20 year old vehicle - IMO that doesn't make it a POS American product, just a really old one. Many parts (particularly the wiring harness) may be original from the factory. Sometimes things break one after another, just due to age, and to make matters more frustrating sometimes the broken parts can yield the same symptoms you were trying to fix to begin with. It gets frustrating really fast when you can't figure it out. Oh the stories I could tell you about my Carter BBD...

You haven't exhausted your options to solve this mystery and keep the Jeep. You may have an issue in the ignition circuit - maybe faulty wiring or a bad ground affecting the coil or other ignition components.
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Unread 04-07-2011, 03:23 AM   #20
yjweber
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Have you checked the timing with a light just to make sure it is correct?

Also, have you checked the dizzy? Is it getting correct power and is it giving off correct power? Is there carbon scoring inside of the cap from it arcing to the cap instead of the posts? How does the rotor look?
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Unread 04-07-2011, 06:12 AM   #21
stoker18
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I wouldn't be so quick to call your Jeep a POS, or to sell it. Replacing the injectors should not keep it from starting. Like NonRubicon said, these things are old. Old wiring and hoses can easily break when you move them around to do repairs.
You said you have fuel and spark but no bang. I know this is a dumb question, but are you sure you have spark?
Is it possible that something was left unplugged/disconnected after your last repair? I know I am pretty good at leaving one little connector unplugged by accident.
Keep at it. You'll get it.
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Unread 04-07-2011, 03:10 PM   #22
kc10er
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well i have calmed down, and want to go wheeling this weekend so................

To answer some questions: First we have not checked timing, I thought it was computer controlled in a 91 yj FI? I also do not see how the timing could jump just because I RnR a fuel rail. I have a friend who was a GM electrical tech. He came over with all his gear (tech 2, test lights, super fancy voltmeter, etc) and we did a lot of tests. Here is what we found;

ALL relays, fuses, fuse connections, and wires running into EVERY plug/connection test good. We broke out the wiring schematic for the whole jeep. He traced things back and tested all of it via the schematic.

We checked spark: Spark at cap and at the plug. He used his fancy inline test kit for spark and the plugs are brand new as of 2 days ago.

I know we are getting gas because my fuel rail pressures up to 31psi with the switch to on, and you can smell gas when you try to start it.

Check engine light is now for some reason OFF with the key in ON! I have ZERO dash warning lights, just flat blank and the volt meter stays at ZERO with key ON.

So we checked the ignition wires and all test good. Now here is the FKed up thing: With the key in ON i can get fuel, it'll spark if we go to START and the starter cranks smooth (new started as of 3 weeks ago). Radio works, headlights/dome light etc all work. So after looking at the ECU "brain surgery" thread I decided I must have blown something because I tested the injectors via a power on unplugging. Plus I replaced them with the battery connected like a moron!

SO....... I have just replaced the capacitors in the ECU and I am waiting for the sillicon (100% silicon) to dry. I will update you guys once I install the ECU in about 3 hours.

Sorry for the hissy fit a few posts back. I just spent so much money on this since purchase doing upgrades and tune-up stuff (6 G's worth) and now that the engine is screwed I am understandably upset. Plus we had a big trip planned for tomorrow! keep ideas coming please, I will be in garage all night!
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Unread 04-07-2011, 03:26 PM   #23
yjweber
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Quote:
Originally Posted by kc10er View Post
Sorry for the hissy fit a few posts back. I just spent so much money on this since purchase doing upgrades and tune-up stuff (6 G's worth) and now that the engine is screwed I am understandably upset. Plus we had a big trip planned for tomorrow! keep ideas coming please, I will be in garage all night!
It is understandable I baught mine for 2g and I have 8g worth of engine work and body work, I havent even spent a dime on lifting it. I put it this way: We YJ guys are buying new jeeps one part at a time.
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Unread 04-07-2011, 06:44 PM   #24
kc10er
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update: so I put the ECU back in, still no CEL light, no start, but still cranks. I cleaned the engine ground on the passenger side of the block where the three ground wires are. Also replaced the metal fuse on the panel under the dash, the old one was rattling so i put in a 10amp one. the old one was a 5.3amp, i am ok with a 10 right? The store did not have a 5.3.

I am freaking lost guys, seriously, how was everything fine, then i put in the rail and now no CEL? Does not make sense and there is no rail ground, etc. Only WIRES removed from rail were the plugs themselves.

ANYONE??????
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Unread 04-07-2011, 08:20 PM   #25
NonRubicon
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Just throwing out some general ideas, someone with more knowledge of the 2.5L could apply them better.

You know fuel is reaching the cylinders. Air is getting in there, according to the compression check. Something is wrong with the air-fuel-spark mixture/timing.
  • You know that there is spark getting to the plugs, but if the spark doesn't get there at the right time then you have a no-go for combustion. Timing chain worn? A different problem with the ECU? Distributor faulty?
  • A weak spark won't be hot enough to ignite the mixture. Weak spark could be caused by poor connection to battery, faulty coil. Loose or corroded battery cables can be a source of weak spark as can faulty wiring.
  • Another possibility - there is an air intake leak that is throwing off the air/fuel mixture.

As unlikely as it may be that some unrelated component decided to crap out on you while you were checking something else, it could still happen. The Jeep was already running odd before this no-start condition popped up.

Futhermore, even if you think you've totally ruled something out, you might have to think again. Keep at it.

An additional thought - it has already been mentioned, but I'm not sure if you've replied to the question: Have you checked the distributor cap and rotor for wear/arcing damage? A bad cap/rotor may send spark out, but not consistently to the right cylinder.
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Unread 04-08-2011, 08:58 AM   #26
kc10er
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My timing is automatic/electric/controlled by ECU. No way to adjust it per the Haynes manual.

All cables are good see above post on wiring check.

No air intake leak

Remember it is not that it is runningbadly now, the ECU won't work or something cause i get no dash lights!.
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Unread 04-08-2011, 09:11 AM   #27
YJWralph
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Quote:
We YJ guys are buying new jeeps one part at a time.
Couldn't have said it better myself. I am putting off mods to catch up with maintenance...
Not too long ago, I had similar no start symptoms. There were gas-soaked plugs and spark but no fire. Put new plugs in, and she almost fired up. Long story short, it turned out to be the ignition coil. Simple and cheap fix...

Could also be the stator in the distributor. That's essentially your camshaft position sensor. Chapter 5-9 in your Haynes book.
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Unread 04-08-2011, 09:43 AM   #28
Que89YJ
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Do a search, the rough idle is probably an Iac issue. Common problem and easy enough to take care of by cleaning both the IAC and the throttle body. If you had a difference before when it was cold and warm also replace the temp sensor by the thermostat. Its also a common fail issue and no before you ask a bad sensor will not always throw a fault code. Also, like it was pointed out, check your vacuum line by using a can of carb cleaner and lightly spraying around your vacuum lines and your manifold to look for leakes. The 2.5 and 4.0L will run for a long long time as long as they are maintained. Where are you losing oil?
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Unread 04-08-2011, 01:05 PM   #29
kc10er
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ok so i fixed the "no CEL light with key ON" problem, now back to the same problem of crank and no start. Good to know my ECU capacitor replacement went ok cause i get CEL now . So I guess I will replace the coil first, why it might have gone out after injector replace i dunno. After that i guess new distributor? OH i looked in the cap though and it is all clean and looks brand new so i don't know if it could still be bad.

EDIT: coil, cap, and rotor replaced. still no start. Replacing the CPS, TPS, and intake temp sensors in a few mins.

Que89yj: I cleaned all sensors in the TB and intake with carb cleaner. Vac lines (ALL) will pass air when i blow through them so that has been checked. It should still start at least if vac line is leaking, might die, but should fire i would think. I am losing oil from (i think) the head gasket at the rear of the block. if it is not that then it is the rear main.

Gonna check to see if i can get a new coil right now. More suggestions please, i feel we are almost there.

Last edited by kc10er; 04-08-2011 at 02:17 PM..
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Unread 04-08-2011, 05:08 PM   #30
kc10er
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ok.... had a mechanic of 30 years from jeep come to the house after work. Nice guy by the way, he offered to come over after i talked to him for the first time today. Anyway, it seems we are not getting fuel now. I replaced EVERY sensor on the whole engine as well as a whole new ignition system today so i know we are good there. The mechanic said since it tried to fire on carb cleaner (just one little da da da) that we are not getting fuel now. So.. tomorrow i am gonna check the injector ground circuit to make sure it is good. Then i am gonna borrow his injector test kit and make sure the injectors themselves are good. If all is good there, then that only leaves one thing; the PCM fuel contoller went out. That means new PCM/ECU is needed.

On that note: anyone got a FI 2.5L 4 cyl YJ ECU for sale??????
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