and yup, ... I know, I know .... I'm a dinosaur, right?

 

OK its a link count yes that is a good way to verify but just align the marks center line of cam and crank and your good

and I still have a light to but it only gets used on my sons 383stroker

 

[quote=vistacruiser;266162]and yup, ... I know, I know .... I'm a dinosaur, right? [/quote
Not yet vista just expirienced! lol I was reading some of the thread again and it still sounds like timing, like mike said "dist out 180 degrees" . the engine has fuel,spark, compression.....dist out a couple of teeth???? I don't know..............

 

IIRC, Mike37, the dots on the gears don't line up when the motor is at TDC on the comp. stroke like they would on your son's stroker or a Ford or just about everything else that I can think of right now. The reason is because of where the keyways are located on the cam and crank.

This is also the reason that you line up the dots on the gears while the chain and gears are lying flat on the floor altogether as a unit then rotate them all together as needed as a unit to get them onto the engine... it's a wierd deal ... I did my own about exactly a year ago ... had the oil pan off anyway and it just seemed like the thing to do to change that stuff out ... had 255K on it then. The rubber slap bumper had busted off of the timing cover too and it was lyin' in the pan ... lol ... hard as a rock. Put an Melling HV oil pump on it then too ... been a year now and I've been just sittin around ...waitin' for it to fail, FrankZ ... bitin' my nails wonderin' when??? ... aw, shoot ... couldn't resist.

They need to use the strobe here for a look-see, as I explained earlier. If a few degrees of advance can be seen then the timing is good and can be eliminated ... then its gonna' be about the infectors cuz that's all that's left of the 'big four' ... earlier she stated that they shoot a stream ... IIRC, they gotta spray a fog in a cone, don't they?

 

you can line up the mark on a 4.0 its just that none of the manuals tell you you can
I think its cus the crank and cam are not vertical
there was a good wright up on NAXJA on it but I cant find it now

there is a link count or pin count on a sbc if you want to wast your time doing it

 

Well, it could be, Cap'n ... but I don't think it would run at all if it were a full 180 out, would it? ... and it is running, she says. Do you think that that PCM computer smart enough to compensate for that much mechanical timing error? I don't know for sure ... but, heck, you might? She had said in an earlier post that they tried switching it 180 degrees and that it didn't work at all then ... wouldn't even start ... go figure??

I wish I had a wireless robot that was right there, on location, with a TV camera and nimble fingers ... by gosh ... that would be the ticket, eh?

 

My manual states that with number 1 at TDC the marks on the gears should be directly opposite each other. The cam gear dot at the bottom and the crank gear dot at the top with a straight line through the centerlines of both gears and both dots. Then it goes on to tell about the link counting way to verify.

 

Is it possible that the CPS and the flywheel are from different years and causing the timing issues? Is the air-gap on the CPS adjustable? A new one comes with a paper spacer that should be left on during installation. Would installing a used one without the spacer cause the gap to be too small?

 

Yup, ... Ol Blue and Mike37, thinking back on it I realize you two are right and I am incorrect about this ... just pulled out the book again too ... lol... I was thinkin ... and that's trouble sometimes, ... lol ... that the marks wouldn't line up til after one revolution ... forgive me, I'm old and got CRS. lol. I'm sure I slid my gears and chain on as a unit though as my book says to do ... went on nice and smooth ... and that left no chance for a mistake.

Blue ... she says that she has matched up the cps and tone ring several times in earlier posts ... no mention of the air gap or paper spacer ... hmmm ... geez .... this is the never-ending-thread-from-hell, ain't it? almost too long to read though it from the beginning at this point ... lol

 

Well I read it but didn't remember seeing what was said about the CPS. I looked in the manual about the timing marks, so I thought I'd look up the CPS also.
When I saw that about the paper spacer I got to wondering what would happen when installing a used one without the spacer. It would/could be too close to the flywheel/tone ring and give erroneous readings, correct?
Maybe something, maybe not. Just trying to give a fresh look at this.
Dan

 

is not only welcome, but sorely NEEDED, Dan ... appreciate the input.

Possibly we could get Karen to spend an hour NOT under the hood to carefully summarize EVERYTHING that they have now done, including sensors replaced, components replaced significant operations and proceedures done and tried and what helped and what didn't, what is still 'in question' and what is not. I think this would be a great help to all of the helpers.

Sometimes, when a thread gets as deep as this one, because of a number of reasons, it is difficult to read through carefully and thoughtfully digest for everyone This is especially true when someone has just looked in for the first time.

I simply refuse to believe that all of the collective talent on this forum cannot help these people get this vehicle running reasonably well. Stubborn, ain't I?

 

I'm simply curious as to the procedure used when re-installing a used CPS. Since the new one comes with the paper spacer attached it must be very important to maintain that precise gap. When installing the used one how can you verify the correct gap? A small difference in that gap can surely make a difference in the signal being picked up, can it not? And an incorrect signal could cause the erratic timing issues that are being seen. As a rough comparison, it's like the old ignition points having the wrong gap. That would make a big difference in the ability of an engine to run properly, if at all. JMO

 

on the gap issue, Dan.

I put a new CPS on my 98 HO, about a year and a half ago and I don't recall a spacer in there, but I got CRS. lol I realize she is working on a Renix ... and is likely different in this regard.

The new CPS may very well be thinner than the original and needs shim to assure that the sensor gets a good, square look at the tone ring. Dunno ... here is the stuff from Alldata on the CPS operation. HO though. so it may not apply ... but it might. Haven't figued out how to get the images in here though ... only the text ...

SYSTEM OPERATION


Crankshaft Position Sensor - Typical
The crankshaft position sensor is mounted to the transmission bellhousing at the left/rear side of engine block.

Engine speed and crankshaft position are provided through the crankshaft position sensor. The sensor generates pulses that are the input sent to the Powertrain control module (PCM). The PCM interprets the sensor input to determine the crankshaft position. The PCM then uses this position, along with other inputs, to determine injector sequence and ignition timing.

The sensor is a hall effect device combined with an internal magnet. It is also sensitive to steel within a certain distance from it.



Sensor Operation



Sensor Operation

Sensor Operation
The flywheel/drive plate has groups of four notches at its outer edge. On 4.0L 6-cylinder engines there are three sets of notches. On 2.5L 4-cylinder engines there are two sets of notches.

The notches cause a pulse to be generated when they pass under the sensor. The pulses are the input to the PCM. For each engine revolution there are two groups of four pulses generated on 2.5L 4-cylinder engines. There are 3 groups of four pulses generated on 4.0L 6-cylinder engines.

The trailing edge of the fourth notch, which causes the pulse, is four degrees before top dead center (TDC) of the corresponding piston.

The engine will not operate if the PCM does not receive a crankshaft position sensor input

 

Renix era has no check engine light, doesn't store codes, and isn't OBD compatible.

I had a very similar issue last year, almost exactly the same symptoms, and went through almost everything Karen is doing, I would like to ask one simple question of Karen. And surprisingly, it is a question nobody else has asked in 6 pages.

WHAT IS YOUR FUEL PRESSURE? Should be about 31 psi with the vacuum line attached, about 39 without. Checking the schrader valve and seeing a spray off it is NOT a good verification of enough fuel. I did that and kept thinking it had to be something other than fuel. USE A PRESSURE GAUGE! Just FYI, Harbor Freight carries a cheap set for about $15, and a "Master" kit for about $80. I now have the $15 set...

Last year, I changed every single sensor, swapped distributor, changed the throttle body, replaced the fuel injectors (but I need to get some new ones), swapped out the ignition module. My XJ is a 90, the parts XJ I had was a 87 that I was swapping parts around with. All Renix. I now have an excellent pile of trail spares to carry in the truck. I had bad compression and changed the headgasket, all with no real overall change. Believe me, I feel your frustration.

What was my problem? When I had swapped EVERYTHING else out, I was going to swap fuel pumps. When I pulled the pump, the little rubber hose on the pump *IN THE TANK* was rotted, and slipped right off the fittings. New piece of hose, and the truck ran just fine. Started easily, ran smooth, no backfiring, ran like a hotrod.

NOT to say this is you problem, but another thing to consider. BUT!!! More than a couple people here have had similar issues with that chunk of hose. The pump is simple to get to for the Renix era, don't need to take the tank out, just be bit of a contortionist. If I can get my 6'3" 300# self in there to get the pump out, anyone can. With little to no fuel in the tank, it is even better time to do this. Check its pre-filter too.

Also, have you replaced your fuel filter? If it is old, hasn't been changed as far as you know, it is something that could be an issue. Case in point. We had the engine out of our Ford Ranger project for 9 months. When we put it back in it would crank but wouldn't start. Barely a trickle of fuel was coming through. New filter and it started right up.

 

boss. lol.

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