Ecomike
NAXJA# 2091
- Location
- MilkyWay Galaxy
:shiver:, Not good!!!!
bcmaxx said:
misfire on renix 4.0 on hot startup
- Thread starter Tito_73*
- Start date
88 Wagonman
NAXJA Forum User
- Location
- Boise, ID
What brand of pump? I had the same thing happen on one that I got from NAPA. It lasted a very short time. I've got a bosch in there now.
90Blue_XJ
NAXJA Forum User
- Location
- In yer postz fixin yer spellinz.
Where did you find a Bosch? I have a NAPA pump and it has been fine for 2 years but I always like to keep a spare in my inventory and ever since I had my first German vehicle I have liked Bosch quality.88 Wagonman said:
bcmaxx
NAXJA Forum User
- Location
- The West Kootenays,B.C. Canada
napa pump
SPSERG
NAXJA Forum User
- Location
- Massachusetts
So hasanyone EVER actually fixed this problem? I have been chasing my tail and replacing parts in an attempt to fix this hot-start issue.NOTHING SO FAR!!!
Ecomike
NAXJA# 2091
- Location
- MilkyWay Galaxy
Might be better to start a new thread, and tell us exactly what it is doing, and exactly what you have tried. Only hot engine renix miss fire problem I ever had was a bad IAT, Air temp sensor in the intake manifold. I take yours is a renix, but we need the year, auto or manual Trans...
MJR
NAXJA Forum User
- Location
- Costa Mesa, CA
Mine just doesn't like to be run hard, then shut off, and restarted within a short period. I'm sure it's vapor lock due to the heat. I insulated the rubber fuel supply line with foil/fiberglass sleeving. Can't think if it's done it since I did that. Insulating the lines and rail/injectors might fix it assuming the fuel pump check valve (part of the pump), regulator, or injectors aren't bleeding pressure off.
SPSERG
NAXJA Forum User
- Location
- Massachusetts
My apologies to all... yes, I should have started a new thread but my frustration level has been through the roof! 1988 XJ, 170K, 5 speed BA trans and I have owned it for almost 10 years. This was my primary transportation until 2010 when I bought a new Lancer Ralliart, now I garage the Lancer and drive the XJ in the winter. Let me preface the problem first by parts: I have replaced ALL of the electronic sensors (O2, knock, IAC, TPS, EGR ETC ETC) within the past 2 years and prior to this engine problem. Also, the fuel pump, fuel tank, injectors (Ford 5.0) throttle body, and MAP sensor. All of the emissions tubing and vapor canister plus the cat convertor. In my prep for this winter, I replaced and gapped all 6 plugs/cap&rotor, wires and fuel filter. Also bypassed the fuel pump resistor and changed the ignition coil. NO DIFFERENCE.
Now as to the misfire... yes, its a full on miss and only after a real hot restart. I can drive to work (10mins) no problem but when I drive it a bit hard or for a longer distance, if I shut it off and say run into a store- when I come out and restart it: It will crank, start but it misses horribly and is obviously not running on all 6 cylinders. Give it a moment of spitting and it will clear itself out but don't plan off jumping in and driving off. This is a full on miss and I can feel that poor motor banging around in its mounts. Occasionally, if I have a long highway drive, when I get back into stop and go traffic I can start to feel the miss while i am waiting at a red-light (no shutdown) but I don't do too much highway driving so this is few and far between. Otherwise, the Jeep runs great, not a single hiccup. Burns no oil, all fluids are good- I would and have driven this vehicle across country...
This has got to be thermally induced, and I considered the vapor lock possibility but for 8 years this XJ never exhibited any of these problems. Since I bought 8 injectors when I swapped them out, I am taking the 2 left-over injectors and using them to replace 2 at a time. So far cylinders 5/6 and no difference whatsoever. Fuel pressure runs at about 38 psi with vac line disconnected, and 31 with. Itdoes not bleed off within the factory time frame.
So, I have searched and searched- but has anyone actually found the root problem for Renix hot start problems? I am sure they are all different, but I would be interested in the solutions since it might point me in a different direction. Thanks, and sorry for the frustration
Now as to the misfire... yes, its a full on miss and only after a real hot restart. I can drive to work (10mins) no problem but when I drive it a bit hard or for a longer distance, if I shut it off and say run into a store- when I come out and restart it: It will crank, start but it misses horribly and is obviously not running on all 6 cylinders. Give it a moment of spitting and it will clear itself out but don't plan off jumping in and driving off. This is a full on miss and I can feel that poor motor banging around in its mounts. Occasionally, if I have a long highway drive, when I get back into stop and go traffic I can start to feel the miss while i am waiting at a red-light (no shutdown) but I don't do too much highway driving so this is few and far between. Otherwise, the Jeep runs great, not a single hiccup. Burns no oil, all fluids are good- I would and have driven this vehicle across country...
This has got to be thermally induced, and I considered the vapor lock possibility but for 8 years this XJ never exhibited any of these problems. Since I bought 8 injectors when I swapped them out, I am taking the 2 left-over injectors and using them to replace 2 at a time. So far cylinders 5/6 and no difference whatsoever. Fuel pressure runs at about 38 psi with vac line disconnected, and 31 with. Itdoes not bleed off within the factory time frame.
So, I have searched and searched- but has anyone actually found the root problem for Renix hot start problems? I am sure they are all different, but I would be interested in the solutions since it might point me in a different direction. Thanks, and sorry for the frustration
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Ecomike
NAXJA# 2091
- Location
- MilkyWay Galaxy
First off, don't assume 2 year old, or even 1 day old parts are GOOD!!!! I recently had a brand new CPS that worked one minute (to start) and the next minute would not start. After weeks of closely watching, I found it infinate resistance one day on the no start, then 2 cranks later it started, and it was back to 275 ohms. So it had a loose, intermitant wire connection internally from the supper fine coil wire to the 22 gauge connector wire internally. Try removing and cleaning the CPS magnetic tip of any magnetic dust from the clutch operation that is dropping the idle signal strength. Have done the Renix CPS mod to boost signal strength of the CPS? Disconnect the CPS, probe it with a meter set for 1.0 AC volt range, and if the cranking voltage is below 0.50 V, your problem is at least partly there. The new after market CPS's are nototious for weak signals.....more on the CPS mounting mod later, if needed......
Take a hair dry and the cold engine, and super heat one part at a time, start with the CPS, then the HV coil ICM assy, and work your way around, heat up one part and then try to start it. Could the EGR being sticking. or the EGR solenoid valve (it is an electric vacuum port valve), check one time to see if the fuel pressure regulator is leaking fuel into the vacuum line (I had an idle miss that was caused by this yesterday, I just fixed it).
Try cleaning the throttle body and IAC valve...but also, not that I think about, it could be a relay on the start up IAC reset that is at issue.
Have you gone through and tested, and fixed all the sensor grounds!!! They are the most notorious cause of Renix problems. See the Sticky thread up top, Cruisers TPS ....testing......
Also, what is the status of your C-101 connector, which is known for having signal and ground loss issues?
Take a hair dry and the cold engine, and super heat one part at a time, start with the CPS, then the HV coil ICM assy, and work your way around, heat up one part and then try to start it. Could the EGR being sticking. or the EGR solenoid valve (it is an electric vacuum port valve), check one time to see if the fuel pressure regulator is leaking fuel into the vacuum line (I had an idle miss that was caused by this yesterday, I just fixed it).
Try cleaning the throttle body and IAC valve...but also, not that I think about, it could be a relay on the start up IAC reset that is at issue.
Have you gone through and tested, and fixed all the sensor grounds!!! They are the most notorious cause of Renix problems. See the Sticky thread up top, Cruisers TPS ....testing......
Also, what is the status of your C-101 connector, which is known for having signal and ground loss issues?
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MJR
NAXJA Forum User
- Location
- Costa Mesa, CA
The reason I added the insulation on the rubber fuel lines along the frame frame in the engine compartment at the time I was replacing a cracked exhaust manifold. Certainly leaking exhaust gas can raise underhood temps. I can't say I've noticed the problem on mine since but I haven't been looking for it to happen. Since yours is doing it while driving (I've never had that happen) you might be looking at two different but seemingly related issues. One is the hot soak and another could be ignition related.
As suggested above by Ecomike you might check your CPS voltage (Renix models only). During cranking and a AC voltmeter on it the voltage it generates should be .5V or higher. Personally I think the sweet spot is .8V but doing the love tap one has to be careful not to go too far or the CPS will Hit the flexplate/flywheel damaging it.
Also don't use Autolite or platinum plugs, just plain Champion copper core (RC9YC) or NGK V-Power (FR5) for Renix models.
Also a word of caution if you've replaced the fuel pump and only the pump I've seen the rubber hose blow off the metal line in the tank. The metal line isn't barbed so it doesn't hold well with the one clamp they give you. I use two fuel injection clamps to make sure it stays put.
I'm pretty much a fan of using OE parts for some stuff because the quality can be much better in some cases (take heater valves for example if you have experienced an aftermarket one start leaking in short order after replacing it).
As suggested above by Ecomike you might check your CPS voltage (Renix models only). During cranking and a AC voltmeter on it the voltage it generates should be .5V or higher. Personally I think the sweet spot is .8V but doing the love tap one has to be careful not to go too far or the CPS will Hit the flexplate/flywheel damaging it.
Also don't use Autolite or platinum plugs, just plain Champion copper core (RC9YC) or NGK V-Power (FR5) for Renix models.
Also a word of caution if you've replaced the fuel pump and only the pump I've seen the rubber hose blow off the metal line in the tank. The metal line isn't barbed so it doesn't hold well with the one clamp they give you. I use two fuel injection clamps to make sure it stays put.
I'm pretty much a fan of using OE parts for some stuff because the quality can be much better in some cases (take heater valves for example if you have experienced an aftermarket one start leaking in short order after replacing it).
Ecomike
NAXJA# 2091
- Location
- MilkyWay Galaxy
I have been using Autolite single electrode platinum plugs on both my Renix jeeps, 87 and 89 since I bought them, with no problems. Several of us here have had no problems using the Autolite single platinum tip spark plugs on our Renix jeeps, and prefer them.
Both of my new CPS sensors get 0.50 volts while cranking, and start up just fine. They are both mounted closer to the flex plate to bost the single from about .25 volts to .50 volts, by drilling out the CPS mounting hole with the next larger drill bit (larger than stock hole), and pushing the CPS closer the flex plate while tightening the bolts.
Both of my new CPS sensors get 0.50 volts while cranking, and start up just fine. They are both mounted closer to the flex plate to bost the single from about .25 volts to .50 volts, by drilling out the CPS mounting hole with the next larger drill bit (larger than stock hole), and pushing the CPS closer the flex plate while tightening the bolts.
MJR
NAXJA Forum User
- Location
- Costa Mesa, CA
I can only speak from my experience as a Chrysler/Dodge/Jeep mechanic since '94 that the Autolite plugs usually cause problems but I'm glad they've been working for you Ecomike. The 4.0L runs just fine on regular plugs and generally doesn't like platinum ones so they are not worth the expense IMO. The only plugs recommended by Jeep are plain Champion or V-power NGK for 4.0L use.
It isn't necessary to drill the holes out the adjust CPS voltage. Any signal voltage below .5V can create a no start or intermittent problems, so at .5 or above is just fine.
It isn't necessary to drill the holes out the adjust CPS voltage. Any signal voltage below .5V can create a no start or intermittent problems, so at .5 or above is just fine.
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Ecomike
NAXJA# 2091
- Location
- MilkyWay Galaxy
Drilling them out, and mounting them closer seems to be needed now days, as the ones being sold today barely produce .25 V when installed in the OEM position.
I have about 60,000 miles on the Autolite single platinum plugs I installed in 2004 on my 87. They still look newish. It has 287,000 miles on it now. But it is the only platinum plug I know of that is reported to work on a Renix.
MJR
NAXJA Forum User
- Location
- Costa Mesa, CA
OE or aftermarket?
Ecomike
NAXJA# 2091
- Location
- MilkyWay Galaxy
Mine were AZ (6 years on the first one at .17 V, and it actually worked at that volatge, which is odd....., then the second was .25 V, but had frequent no starts, which turned out to be a bad internal electrical connection that would make one minute, then open the next on start attempts, I disected that one....plan to post photos one of these days...), then most recently Standard Products from Rock Auto, which have worked flawlessly, but I mounted them about 1/16" closer to the flex plate which doubled the voltage. I never buy anything OE, OEM if I can avoid it. There is serious doubt that a Renix dealer CPS is anything other than aftermarket stuff these days, since they are not required to support the parts market after 7 years.
Crueser54, who was a Jeep service manager at one time, IIRC says that the dealers even mounted the OEM CPS closer to get out of a warranty bind, IIRC.
Crueser54, who was a Jeep service manager at one time, IIRC says that the dealers even mounted the OEM CPS closer to get out of a warranty bind, IIRC.
MJR
NAXJA Forum User
- Location
- Costa Mesa, CA
I use OE most of the time and they can be better quality as I've seen but bad they cost so much more for most people. We didn't open up the holes just adjusted with a pry bar and hammer.
Ecomike
NAXJA# 2091
- Location
- MilkyWay Galaxy
Opening up the holes is a lot safer, not as fast if already installed, but safer. I tried both. I think Cruise54 mentioned the Hammer approach as well, LOL, now that you mention it. I always wondered why those dealership mechanics at the dealership were so expensive? LOL, guess it was because they knew where to hit with the HAMMER!!! LOL:yelclap:
bcmaxx
NAXJA Forum User
- Location
- The West Kootenays,B.C. Canada
Any updates from anyone? condition still exists on mine :flamemad:
cruiser54
NAXJA Forum User
- Location
- Prescott, Az
Renix CPS Testing and Adjusting
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 11-29-2011
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
Revised 11-29-2011
cruiser54
NAXJA Forum User
- Location
- Prescott, Az
Cruiser’s Renix Sensor Ground Test
Set your meter to measure Ohms. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.
Set your meter to measure Ohms. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.
