inliner

Got suckered into helping a neighbor with his 89 Jeep Cherokee Pioneer, 4.0 with Renix system & auto trans.
It had been sitting out in the open, with the hood off & no engine in it for about 2 or 3 years, so I'm told. I did a mild port & polish on the head & proceeded to stab the engine back in with minimal difficulty. Checked out all the sensors before mounting them & they were all within posted operating tolerances. After getting every thing hooked up, I'd have fuel pressure, & engine would crank, but not start. I went ahead & tracked down a RENIX Code Reader & it determined that the Crank Position Sensor was not being read. After further investigation, I found that the CPS was no longer being run through the harness, but through the firewall straight to the ECU. After plugging the CPS into the modded location, I tried running the RENIX Code Reader again. I keep getting a "NO Responce from Logic Mod/SMEC/SBEC. Key ON/Crank Eng, or Enter for Carb Menu" . The neighbor/owner decided to go ahead & purchase a new ECU. While he was doing that, I checked for coninuity from the ECU port on the Harness to the Code Reader Port in the engine bay, all appeared to be normal. I then installed the new ECU, connected the battery terminals, installed it, proceeded to run the RENIX Code Reader and it started to do the usual analysis as it should, up until the "Key On" point. When I got to the "Key On" Portion, it had begun to rain, so I powered every thing down & called it a night. This evening, I tried to start over & got the "NO Response from..." again. ANY HELP would be greatly appreciated. THANKS!!!

inliner

Engine cranks, but no start. I have two different Jeep/Eagle DRB II adapters, along with the DRB II & a 87-90 Jeep/Eagle Cartridge & 83-93 Super Cartridge. I'm beginning to guess that there's an intermittent short in the cables.

inliner

Key on, fuel system pressurizes, engine cranks but no spark. I noticed when stabbing the distributor that it either lands before or after #1. Any one know which it should be?

5-90

Bear in mind that ignition should fire just a few degrees before TDC...

As far as the rest - you said, "It had been sitting out in the open, with the hood off & no engine in it for about 2 or 3 years ..." That tells me you've likely got a number of wiring faults caused by exposure to the elements. The ECU is underdash (down by your right knee,) but the ICM is still underhood - and could have been screwed up. Running the CKP harness directly to the ECU is a common fix for a weak CKP signal, and was covered in a TSB as a bypass for the C101 connector through mid-1988 (and it sometimes cropped up as a problem through 1990.)

Most RENIX troubleshooting can be done handily with a DMM anyhow - cruise on in to my RENIXPower group (groups.yahoo.com/group/RENIXPower. Make sure you tell us why you're there - I had to switch to Full moderation because of the SPAMmers. I've got a few "assistant listmoms" there, so you should get in fairly quickly...) and you can download the old RENIX FI manual (which gives you more useful information than the FSM does, and makes a useful adjunct.)

But, start with a thorough visual inspection of the wiring, paying particular attention to any bulkhead connectors! The component connectors are pretty much all Delphi Weatherpacks, and are usually proof against mild exposure (and immersion, and weather, ...) but the bulkhead connectors are not. Disassemble the bulkhead connectors for inspection, and clean them out! The OEM anticorrosive will end up as a contaminant, and should be removed. I believe dielectric grease makes for an effective replacement - can anyone confirm? (I plan to redesign my setup to use either Amphenols or CPCs - both of which are proof against damned near anything without chemicals added. I'll take 'em!)

inliner

Thanks, will verify the distributor this afternoon. I was able to download the RENIX Manual & have read over it. I've yet to verify the Cam Position Sensor. . I was some what surprised that the Crank Position Sensor connectors on the harness were still present after reading the TSB Bypass. The ICM appears to be getting power, how ever I'm not seeing spark. I had told my neighbor that since the vehicle had been out in the elements that the wiring would be a big issue. I don't think he really understood that. Been telling him to be patient, I'd rather verify wiring than go out & randomly buy parts... LOL. I appreciate the info!

Bustedknuckle

Very interesting thread. Keep us posted, good luck!

kbad

hey man....look here for renix troubleshooting tips..... http://www.lunghd.com/On_Site_Tech.htm ....good luck!

fantic238

Do you have an oscilloscope? No? not a problem...

Il' tell you how to do the same things you can do with a 3000$ oscilloscope using a 5$ chinese analogic tester instead. It must have the needle, no digits.
If you have one you can check if the ignition coil is receiveing the square wave signal from the ECU.

Stick the positive lead into pin B of connector 2 of the ignition module and the negative to mass. Switch the tester to the lowest DC Volt range you have, usually 100 millivolts, and crank the engine. If the needle moves up and down you have the square wave.
Nothing? follow the wire to the ECU and check pin D13 of the ECU harness:
signal yes= wire broken somewhere
signal no= CPS input bad.

Same procedure to check the CPS: positive lead into pin C1 (violet wire) of the ECU and negative to mass
signal yes= ECU is either shot or not fed, in this case you would also miss injector spray.
signal no= CPU is either bad or wire is interrupted.

Before you perform these tests, you MUST check the following:
-CPS resistance (don't remember how much it should be, but that's something you find every manual)
-CPS mass (white wire) must be a mass when ignition is on (ECU pin D1), if it's not jumper to mass.

-Ignition module must have positive feed on connector 1, pin A when ignition is on, if not jumper to positive on batt.

-Ignition module must have negative feed on connector 1, pin B when ignition is on, if not jumper to mass.

If you have all the above working, distributor correctly indexed and decent fuel pressure the engine MUST start, unless some gremlins ate the pistons off the rods like we would do with a chicken leg... yummy.

fantic238

The important stuff:

inliner

Thanks guys, I've got copies of the system schematics, and both an analog & digital multimeter. I'll be working on it this weekend & keep you guys posted.

inliner

What are you referring too when you say connect the negative to "mass"? Been looking over the rest of the info & not sure about what you meant.

THANKS!

89Laredo

he means ground.

inliner

Thanks Defiance, it's pretty much what I figured but wanted to make sure before I got started with it. I've never heard of ground referred to as mass before...

fantic238

Yes Defiance is correct, what i call mass is commonly referred as to ground, it's engineering language meaning the metallic mass (body) of the car.

5-90

Hm. Makes sense, I just never picked that one up. I tend to refer to it as "earth" (but I also refer to "gudgeon pins" - spent way too much time in England and Australia...)