2.5 Timing Problem?

[wooky48]

Going over my "new" '89 MJ with a fine tooth comb 8) I've put new plugs, wires, cap, rotor, and intake/exhaust gasket (among several other things). While doing all that I found the distributor to be 180 out. It'll start right up but idles rough as hell and no power riding around the yard (vacuum lines checked), if I take off the vacuum line that runs over to the passenger side of the engine bay (other line at this port goes to EGR) the idle smooths out just a bit, removing EGR line has no effect. I was planning on resetting the distributor anyway (so nobody else loses hair), could the rough idle be from it being a tooth off? (PO obviously wasn't too mechanically inclined). I know (from the book and here) that the timing is not adjustable (TBI).

 

:bowdown: Thanks in advance for any second opinions on this

[jaekl]

Check the compression. I had holes in 2 pistons. It ran smooth enough, just not much power.

[wooky48]

Check the compression. I had holes in 2 pistons. It ran smooth enough, just not much power.

Surprisingly enough the engine ran smooth just before the tune up parts were installed, when I could get it started. The reason for the fine toothed comb is from so many items needing attention, new PCV with no hose hooked to it, smashed air box (no filter), obvious exhaust leak at the manifolds. PO parked it, from my understanding, due to the hard starting. I'll borrow a compression tester from a guy at work and let you know.

[brigarpeon]

Yes it can be rough a tooth out. Phase the rotor to the cam. Remember the rotor should be 10 - 12 degrees past the distributor post, not before it, at TDC, to be phased correctly.

[wooky48]

Yes it can be rough a tooth out. Phase the rotor to the cam. Remember the rotor should be 10 - 12 degrees past the distributor post, not before it, at TDC, to be phased correctly.

Not sure what you mean by "phasing", I thought that at TDC the rotor should be lined up with #1 wire post on the cap since the computer takes care of all engine functions.

[Eagle]

Yes it can be rough a tooth out. Phase the rotor to the cam. Remember the rotor should be 10 - 12 degrees past the distributor post, not before it, at TDC, to be phased correctly.

Not sure what you mean by "phasing", I thought that at TDC the rotor should be lined up with #1 wire post on the cap since the computer takes care of all engine functions.

Only in theory.

 

In practice, all engine run with a bit of advance, meaning they fire the spark plug before the piston reaches TDC (top-dead-center) to allow for the air-fuel mix to start burning. The idea is to have the mix fully ignited so the flame front gets to the piston when the piston is at TDC.

 

In order to build in some physical advance, the distributor is set up so that the tip of the rotor crosses the contact in the cap before the crank reaches TDC. It's hard to set that, so it's easier to set the timing mark on the harmonic damper to the TDC mark, and then align the distributor so the tip of the rotor is slightly beyond (in the direction of rotation) the contact in the cap.

 

Are you certain your distributor is 180-degrees out? It shouldn't run like that -- that would make every cylinder fire when the piston is on the exhaust stroke.

 

Jeep uses the term "indexing" the distributor, not "phasing." There is a TSB out for indexing the 6-cylinder distributor. I'm not aware of one for the 4-cylinder, but the concept would be the same.

[brigarpeon]

Yes it can be rough a tooth out. Phase the rotor to the cam. Remember the rotor should be 10 - 12 degrees past the distributor post, not before it, at TDC, to be phased correctly.

Not sure what you mean by "phasing", I thought that at TDC the rotor should be lined up with #1 wire post on the cap since the computer takes care of all engine functions.

Phasing is where the rotor is in relation to the distributor post at TDC for all cylinders in their sequence. When the cylinder fires, the rotor has already moved past the point where it ignites the compressed charge. If it is phased before TDC it will spark before the piston is at the top of the stroke. The computer does take care of the fire position but it is based on TDC and the components in the correct position, it will allow for several degrees of change. If the rotor is phased before and the computer sees TDC IT WILL fire at 8-10 degrees before. Whereas set correctly it will fire when the COMPUTER sees TDC through the CPS, which in reality is around 10 degrees after. So, Yes it will line up with the #1 post but it's all about where on the #1 post. The ECU can handle small variation but not 20 + degrees of variation.

[wooky48]

I have the old rotor in front of me and the new one is identical (I always check parts before installing). The actual "tip" is about 3/4 inch long. When I changed everything out the other day #1 plug was hooked to #1 (marked) cap post, then 3, 4, and 2 to their respective plugs, nothing fired, after rechecking TDC, #1 plug was "firing" at #4 cap post, hence 180 out. Changed the wires to a 4213 configuration, it started right up but with a real rough idle, even after 10 minutes of running.

[Eagle]

I have the old rotor in front of me and the new one is identical (I always check parts before installing). The actual "tip" is about 3/4 inch long. When I changed everything out the other day #1 plug was hooked to #1 (marked) cap post, then 3, 4, and 2 to their respective plugs, nothing fired, after rechecking TDC, #1 plug was "firing" at #4 cap post, hence 180 out. Changed the wires to a 4213 configuration, it started right up but with a real rough idle, even after 10 minutes of running.

So you moved the wires rather than reset the distributor? Doesn't the 4-cylinder have a camshaft position sensor in the distributor, like the 6-cylinder? If so, you may now have the spark out of synch with the cam position sensor.

[wooky48]

So you moved the wires rather than reset the distributor? Doesn't the 4-cylinder have a camshaft position sensor in the distributor, like the 6-cylinder? If so, you may now have the spark out of synch with the cam position sensor.

Camshaft position sensor, :???: I have no idea. When I moved the wires I was just wanting to see if the run of the engine would be better (hard start issue) and it did fire right up but with the rough idle which improved slightly when I took the vacuum hose off

[Eagle]

Okay, guys -- SOMEBODY who has a running 2.5L with the stock distributor, please put the #1 cylinder at TDC on the compression stroke and tell this man where the rotor is pointing. Better yet, take a photo.

 

I would do it, but none of my 4-cylinder MJs is running at the moment.

[wooky48]

Ok everyone, I flipped through the repair book I have here again (when all else fails.....), I see what was meant by the term "phase". Gonna R/R the distributor tomorrow afternoon. I am better at being a parts changer than a mechanic (yes there is a difference :wrench: )(and yes, I work on my vehicles under a shade tree :nuts: )

 

Eagle, I didn't see anything in the book about a cam sensor for any of the engines, but then again I have 2 books on my sterndrive and there are some things covered in one that isn't covered in the other. Thanks to the fresh insight and input from all who responded

 

On the 4 cylinder at #1 TDC the rotor should point straight away from the block when the distributor is fully seated. What I observed the other day is that yes it is off by a tooth or two. The engine should run smooth as glass when I'm done tomorrow, I'll let yall know.

[brigarpeon]

TDC SENSOR

The TDC sensor senses TDC and BDC crankshaft positions as

well as engine RPM. Sensor is located on left rear side of engine and

is not adjustable. Sensor is secured by special shouldered bolts to

flywheel/drive plate housing.

TESTING

1) Disconnect ignition coil wire from center tower of

distributor cap. Using insulated pliers, hold coil wire about 1/2" (13

mm) away from engine block. Crank engine and check for spark between

wire and engine block.

2) If spark occurs, reconnect coil wire to distributor cap.

Remove spark plug wire from one spark plug. Using insulated pliers,

hold wire about 1/2" (13 mm) away from engine block.

3) Crank engine and check for spark between wire and engine

block. If spark occurs, check fuel system for problems. If no spark

occurs, check for a defective rotor, distributor cap, or spark plug

wires. Replace parts as necessary.

4) If rotor, cap and wires are okay, check for loose or

corroded connections at coil terminals. If necessary, clean terminals

and wires. Ensure wires are properly seated on coil terminals and not

wedged between coil body and terminal. If okay, go to next step.

5) Check for loose connectors at ICM or ECU. Verify that wire

connectors are firmly plugged into ICM and ECU. Also check for loose

ICM or ECU ground wire connections at oil dipstick bracket. Clean and

tighten if necessary.

6) Load test battery to ensure battery is fully charged.

Replace battery if necessary. If battery is okay, check voltage

between terminals "A" and "B" of ICM connector while cranking engine.

7) Minimum voltage reading should be 9.5 volts. If voltage is

okay, go to next step. If voltage is low, check continuity of ICM and

ECU ground wires. Repair or replace as necessary.

8) Using an ohmmeter, check ignition coil resistance.

Resistance on primary winding should be .4-.8 ohms. Secondary

resistance should be 2500-4000 ohms. If correct, go to next step. If

not, replace ignition coil.

9) Check ECU and ICM with Tester (MS 1700). Replace ICM or

ECU if either fails MS 1700 test sequence.

[Eagle]

^^^

 

That's good info, but it's discussing the crankshaft position sensor, not the camshaft position sensor. The cam position sensor (if the 4-cylinder has one) would be inside the distributor. The 6-cylinder Renix models definitely have one.

 

However, the above testing procedure offers NO information on how to actually test the CPS (crankshaft position sensor). That seems to be a more general procedure for trouble-shooting a no-spark fault.

 

The verbiage doesn't sound familiar. Is that by any chance from a Chrysler tech manual for a '91 or newer Jeep? This thread is about a Renix 4-cylinder. Let's not confuse the issue with information about testing the newer Mopar systems.

[mjeff87]

2.5's don't have a cam sensor.

 

Make sure you are on the compression stroke, bring #1 to TDC and verify it by the timing mark on the harmonic balancer (yes, it's there along with the degree scale marker although it's useless for anything other than TDC reference). The rotor tip, if you are looking directly at it from the passenger fender, "should" be pointing at 4 o'clock. Then position the plug wires 1-3-4-2.

 

Jeff

[brigarpeon]

^^^

 

That's good info, but it's discussing the crankshaft position sensor, not the camshaft position sensor. The cam position sensor (if the 4-cylinder has one) would be inside the distributor. The 6-cylinder Renix models definitely have one.

 

However, the above testing procedure offers NO information on how to actually test the CPS (crankshaft position sensor). That seems to be a more general procedure for trouble-shooting a no-spark fault.

 

The verbiage doesn't sound familiar. Is that by any chance from a Chrysler tech manual for a '91 or newer Jeep? This thread is about a Renix 4-cylinder. Let's not confuse the issue with information about testing the newer Mopar systems.

 

1. 4 cylinder does not have a cam position sensor.

 

2. He ask yesterday for the Crankshaft sensor test that was not replied to

 

3. 1988 - 1990 JEEP 2.5L Renix Service Manual

 

4. Some things even I don't know but I admit it.

[wooky48]

2. He ask yesterday for the Crankshaft sensor test that was not replied to

 

I thought for a minute I was losing it :nuts: no I don't recall asking about the test for the TDC sensor (I checked the posts) no point in testing something that you know works. Just got home and fixin' to go get a bit greasy and see if we can fix this thing while I have a bit more daylight.

[wooky48]

Thanks for everyones help, :bowdown: the distributor is now set, #1 firing on #1 cap post and a noticeable improvement in the idle (yes it was 180 and one tooth off). I've never messed with distributors til now and was simply going by the book I have here (and they don't tell you everything)

[Eagle]

"I love it when a plan comes together."

[wooky48]

"I love it when a plan comes together."

 

The A-Team, can't remember the characters name, George Peppard played.

 

Idle is much improved but has a "lope" in it and strong exhaust smell, running rich perhaps (the truck sat for almost 2 years) and with what I've had to "re-repair" so far..... Can of injector cleaner in the tank I think might help.

[brigarpeon]

2. He ask yesterday for the Crankshaft sensor test that was not replied to

 

I thought for a minute I was losing it :nuts: no I don't recall asking about the test for the TDC sensor (I checked the posts) no point in testing something that you know works. Just got home and fixin' to go get a bit greasy and see if we can fix this thing while I have a bit more daylight.

 

Nope your not nuts... I am :nuts:

I posted the Test in your 2.5 thread and it was the "2.5 won't start" thread a bit further down that I meant to post it in. Glad you got it fixed though.

[wooky48]

Nope your not nuts... I am :nuts:

 

Glad you got it fixed though.

 

Well then, I AM in the right place :nuts:

Oh, I fixed AT it, not quite done yet, valve cover gasket, injector cleaner, then gotta get the lights working :eek: :shake:

[Eagle]

"I love it when a plan comes together."

 

The A-Team, can't remember the characters name, George Peppard played.

Colonel Hannibal Smith.

[wooky48]

"I love it when a plan comes together."

 

The A-Team, can't remember the characters name, George Peppard played.

Colonel Hannibal Smith.

Yup, that's him