jbellingham Posted October 17, 2018 Share Posted October 17, 2018 Having some starting issues with my Jeep. Here’s what I’ve done so far: - Fuel Pressure - tests at 30 psi - alternator, battery, starter all test good - new distributer cap and rotor - crank position sensor shows proper resistance when I test with multimeter - truck will usually start with a boost, but will just crank when I start with ignition. Crank is strong - one it starts it runs good without any issues would appreciate any suggestions as I’m stumped... any chance the coil could be the issue?? Link to comment Share on other sites More sharing options...
jbellingham Posted October 17, 2018 Author Share Posted October 17, 2018 Should also say that I completed an engine swap a few days ago - the truck was running and starting fine for a couple days, but then the issue started Link to comment Share on other sites More sharing options...
Ωhm Posted October 17, 2018 Share Posted October 17, 2018 7 minutes ago, jbellingham said: - crank position sensor shows proper resistance when I test with multimeter Set multimeter to volts AC and perform cruisers tip. RENIX CPS TESTING AND ADJUSTING Link to comment Share on other sites More sharing options...
jbellingham Posted October 17, 2018 Author Share Posted October 17, 2018 21 minutes ago, Ωhm said: Set multimeter to volts AC and perform cruisers tip. RENIX CPS TESTING AND ADJUSTING I’ll give that a try, but just wondering whether the Jeep would run with bad cps?? Once I get it started it runs good... Link to comment Share on other sites More sharing options...
Ωhm Posted October 17, 2018 Share Posted October 17, 2018 The slower the trigger wheel spins, voltage (AC) at the CPS decreases. When you jump the battery, does CRANK RPMs increase? Link to comment Share on other sites More sharing options...
coolwind57 Posted October 17, 2018 Share Posted October 17, 2018 I'm actively dealing with a similar problem as well. I was hopeful that I found my problem when I found that I had previously accidentally crossed my #5 & #6 fuel injector connectors. Despite this, she still ran very well over the last 3-months or so. Disappointed that this error was not the reason for my excessive cranking-before-starting issue. 40 minutes ago, jbellingham said: I’ll give that a try, but just wondering whether the Jeep would run with bad cps?? Once I get it started it runs good... I finally got around to checking my CPS AC voltage yesterday. I checked several times and I think .2 flashed for a second at one point, but otherwise the CPS cranked out a consistent .1 VAC. This is NOT a good number. It apparently should be pumping out .5 VAC. So, if .1 is considered "bad", then I've been running with a bad CPS for these past few Months. My only symptom is the excessive cranking before starting (and usually a very prominent odor of gasoline once she does fire to life). I still have what I assume is the original "SIEMENS Made in France" CPS that I replaced last year. I had swapped it during a parts-cannon attempt to solve a previous problem, but I think it is still good. I'm going to install it tonight and see if this resolves my cranking problem. I'm anxious to hear what VAC numbers you're getting out of your CPS. Link to comment Share on other sites More sharing options...
jbellingham Posted October 17, 2018 Author Share Posted October 17, 2018 2 hours ago, Ωhm said: Set multimeter to volts AC and perform cruisers tip. RENIX CPS TESTING AND ADJUSTING I’ll give that a try, but just wondering whether the Jeep would run with bad cps?? Once I get it started it runs good... Link to comment Share on other sites More sharing options...
jbellingham Posted October 17, 2018 Author Share Posted October 17, 2018 Mt cps is only putting out 0.1- 0.2 at crank.... looks like that might be the culprit. I could kick myself now - I just swapped engine last week and thought about switching it out when I had easy access to the bell housing. It’s such a pain to reach.... Link to comment Share on other sites More sharing options...
coolwind57 Posted October 17, 2018 Share Posted October 17, 2018 Also, I'm quite certain that CPS design/function changed a couple times during the MJ/XJ years. An early Renix CPS may not work correctly in a later engine and vice versa. What's the engine swap, exactly? Link to comment Share on other sites More sharing options...
coolwind57 Posted October 17, 2018 Share Posted October 17, 2018 1 hour ago, jbellingham said: Mt cps is only putting out 0.1- 0.2 at crank.... looks like that might be the culprit. I could kick myself now - I just swapped engine last week and thought about switching it out when I had easy access to the bell housing. It’s such a pain to reach.... Yep, I feel your pain. I just happened to run across a small magnet today at work. I glued that sucker inside my 11mm socket, so I'm anxious to swap out my CPS tonight with a tool that is less likely to drop my CPS bolts during the tedious process. Multiple extensions and a u-joint on my 3/8" drive ratchet is how I accomplished it last time. Once, I dropped one of the bolts through that stupid hole on the top of the bellhousing, just beneith the CPS. I completely freaked out and had to open up the inspection cover on the bottom of the bell housing and use a tire iron to carefully pry on the flex plate to provide just clearance for the bolt to come out of the bottom. I nearly lost my religion over that whole ordeal. Link to comment Share on other sites More sharing options...
omega_rugal Posted October 17, 2018 Share Posted October 17, 2018 what about the cam position sensor ? you know the one inside the distributor? if the ecu can´t get a proper sync signal to fire the inyectors it will use a random order, the engine will run but may or may not run right... Link to comment Share on other sites More sharing options...
cody4359 Posted October 18, 2018 Share Posted October 18, 2018 what about the cam position sensor ? you know the one inside the distributor? if the ecu can´t get a proper sync signal to fire the inyectors it will use a random order, the engine will run but may or may not run right... Depends on what year motor, 97+ have them and 96- don't Sent from my SM-G900V using Tapatalk Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 18, 2018 Share Posted October 18, 2018 45 minutes ago, cody4359 said: Depends on what year motor, 97+ have them and 96- don't Huh? The 56027028 distributor is used in most all 1994-1999's models. I have one in my 91 because the cam position sensor sets right on top and is easy to change. Link to comment Share on other sites More sharing options...
jbellingham Posted October 18, 2018 Author Share Posted October 18, 2018 7 hours ago, coolwind57 said: Also, I'm quite certain that CPS design/function changed a couple times during the MJ/XJ years. An early Renix CPS may not work correctly in a later engine and vice versa. What's the engine swap, exactly? Should be ok in my case - I swapped a Renix for a Renix. Ordered my new cps today Link to comment Share on other sites More sharing options...
jbellingham Posted October 18, 2018 Author Share Posted October 18, 2018 Since we’re on the subject of cps, and it looks like I’m installing a new one, has anyone tried cruiser54 timing advance mod?? I’d like to give it a try, but don’t want to mess up my cps. Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 18, 2018 Share Posted October 18, 2018 7 hours ago, coolwind57 said: Yep, I feel your pain. I just happened to run across a small magnet today at work. I glued that sucker inside my 11mm socket, so I'm anxious to swap out my CPS tonight with a tool that is less likely to drop my CPS bolts during the tedious process. Excellent idea. Let us know how it works. Link to comment Share on other sites More sharing options...
coolwind57 Posted October 18, 2018 Share Posted October 18, 2018 8 hours ago, jbellingham said: Since we’re on the subject of cps, and it looks like I’m installing a new one, has anyone tried cruiser54 timing advance mod?? I’d like to give it a try, but don’t want to mess up my cps. Well, I didn't get a chance to swap out my CPS last night. I did perform the advancing mod on my existing CPS and I just performed the mod on the one I'm putting back on tonight. I suppose my case is not exactly the best example since my CPS is apparently bad, but I'm comfortable with doing this. It takes some strong smacks and strong words to get it to move but it'll slide with some persuasion. Just protect your bolt hole by putting a bolt in there before smacking with a hammer. If not, you'll deform it. Link to comment Share on other sites More sharing options...
Jeep Driver Posted October 18, 2018 Share Posted October 18, 2018 9 hours ago, jbellingham said: Since we’re on the subject of cps, and it looks like I’m installing a new one, has anyone tried cruiser54 timing advance mod?? I’d like to give it a try, but don’t want to mess up my cps. You'll gain 1 degree of advance...........eh............. Just get it running, then play. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 18, 2018 Share Posted October 18, 2018 13 hours ago, omega_rugal said: what about the cam position sensor ? you know the one inside the distributor? if the ecu can´t get a proper sync signal to fire the inyectors it will use a random order, the engine will run but may or may not run right... You can disconnect that sync sensor and not notice the difference. It's not a cam sensor anyway on Renix. Link to comment Share on other sites More sharing options...
cruiser54 Posted October 18, 2018 Share Posted October 18, 2018 Even though I've never proclaimed to be a genius, here's something to help keep everyone on the same page. OCTOBER 30, 2015 SALAD 84 COMMENTS EDIT 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 itself as shown in Figure 2 as Connector A, 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 the upper mounting hole to 3/8″ from the stock 5/16″, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts. Another little tip to save tons of aggravation is to stick a bit of electrical tape to your 11mm socket and then shove the bolt in after it. This reduces the chances of dropping that special bolt into the bell housing. Link to comment Share on other sites More sharing options...
Pete M Posted October 18, 2018 Share Posted October 18, 2018 jbellingham , please add some details about your truck to your signature. that'll help keep everyone on the same page. Link to comment Share on other sites More sharing options...
omega_rugal Posted October 18, 2018 Share Posted October 18, 2018 13 hours ago, cody4359 said: Depends on what year motor, 97+ have them and 96- don't Sent from my SM-G900V using Tapatalk all have them, even the one´s that use individual coils, in this case only the CAM POSITION SENSOR aka SYNC SIGNAL with no distribuitor it says right here http://www.lunghd.com/Tech_Articles/Engine/Cam_Position_Sensor_and_Sync_Pulse_Stator.htm Quote - truck will usually start with a boost, but will just crank when I start with ignition. Crank is strong wait, what do you mean by "Boost"? Link to comment Share on other sites More sharing options...
jbellingham Posted October 22, 2018 Author Share Posted October 22, 2018 Hey everyone - installed new cps today (modified according to cruiser’s instruction), and the truck is starting again. Appreciate the help!! Ive got another issue, however, with idling. It idles at about 1000 rpm, then gets bogged down for a few seconds, and returns to normal idle speed. It was doing the same thing with the old engine, so I’m assumbig it must be a sensor... Any suggestions of where to look? At one point I changed both the tps and the idle control valve, but nothing seemed to change. From what I can tell there are no vacuum leaks - I’ve sprayed throttle cleaner all over and haven’t been able to find a leak. I was wondering if air bubbles in the coolant might cause this kind of surging?? Link to comment Share on other sites More sharing options...
coolwind57 Posted October 24, 2018 Share Posted October 24, 2018 hey jbellingham, glad to hear you got er starting! So your idle issue is more than just typical open/closed loop transitioning? You didn't mention addressing or checking your O2 sensor during your swap journey. Along with Cruiser54's tips, I'd look into the O2 as well as the MAP sensor and it's vacuum tube as they are two specific areas that can strongly effect idle issues. By the way, I successfully swapped out my aftermarket CPS with that original SIEMENS CPS that I had saved. I'm now getting a consistent .9 VAC. I had a .7 VAC flash up once, but it's a consistent STRONG .9 VAC. Huge number difference from a consistent .1 VAC on my aftermarket one. I'm still having some delayed starting issues, so it didn't solve my main problem. I think I have some injector issues, as I think at this point I've addressed everything else. So tell us how bad exactly is this idle of yours? Does it just drop down once? Die? Link to comment Share on other sites More sharing options...
cruiser54 Posted October 24, 2018 Share Posted October 24, 2018 This^^^^. Link to comment Share on other sites More sharing options...
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