Fender flair

[Comanche1]

A couple of things I’m wondering about. Will Cherokee fender flairs fit our trucks? And... I want to stop my 2.5 from revise so high on initial start up. Go up to 3000 rpm then back down almost immediately. I hat that initial high rom when oil press isn’t even up yet. 

[rylee144]

Front fenders will rear will not

[Ωhm]

4 minutes ago, Comanche1 said:

And... I want to stop my 2.5 from revise so high on initial start up. Go up to 3000 rpm then back down almost immediately. I hat that initial high rom when oil press isn’t even up yet.

That's kinda of a good thing. Proves Idle Speed Control Motor (ISCM) is working as intended. Keep in mind that the fuel injector is above the throttle plate on 2.5L engines and needs to be open during START.

[Comanche1]

The iscm is new and screwed down as low as possible. I’m getting a low end rattle for a millisecond as it races up to the 3 thousand mark. 

[Ωhm]

25 minutes ago, Comanche1 said:

The iscm is new and screwed down as low as possible.

According to SPEC's, it should soar to 3500 rpms.

 

26 minutes ago, Comanche1 said:

I’m getting a low end rattle for a millisecond as it races up to the 3 thousand mark.

That sounds mechanical or something is just loose.

[Comanche1]

To me it’s a rod bearing with no oil as it goes froM 0 to 3000 with little or no oil pressure in an instant until pump can provide flow. 

[Ωhm]

Yea, many things happen fast on START up. Let's hope its not the "death knock" you hear. Maybe others here have insight to this.

[eaglescout526]

I am confused as to what the outlying problem is here. First it was fender flares. Then 0-3000 RPM on a 2.5L at start up(Normal for Renix) and now we are at no oil pressure at start up. I would like to help but lets put some ducks in a row.

[rylee144]

Google says yes

[Comanche1]

On start up of any engine, while cranking... there is initially no or almost no oil pressure. All of the sudden, my engine is at 3000 as oil starts to flow, as in any engine.  Trying to keep startup rpms down to a reasonable level giving the oil a chance to flow....   as a master mechanic of 45 years and still going strong, I know the need for oil flow on initial start up. I hate the “ instant” 3000 rpm at the first few seconds.       ..... in addition, do Cherokee flairs fit our Comanche trucks. ( it’s a 2 parter) 

[eaglescout526]

Ok makes much more sense now. A good healthy engine will have 50-60 psi at start up and come down to 30-40 psi once at op-temp. I would suspect the oil pressure sending unit or sensor to be faulty at start up or something weird is up with the electrical connection to it. Do you have full cluster package or idiot lights?

 

Rear XJ flares do not fit unless you do some good split down the middle cutting and bonding the complete halves to make a whole MJ rear flare. Time consuming and costly but worth it if you can't find original flares.

[Comanche1]

4 hours ago, Ωhm said:

Yea, many things happen fast on START up. Let's hope its not the "death knock" you hear. Maybe others here have insight to this.

Ya I know that sound. As a professional mechanic I’ve overhauled or had to trash many engines when they get to that point. Slightly different on this one  and only for about 1/2 a second on start if sitting for a few days. 

[Comanche1]

5 hours ago, rylee144 said:

Front fenders will rear will not

Many thanks 

[Comanche1]

30 minutes ago, eaglescout526 said:

Ok makes much more sense now. A good healthy engine will have 50-60 psi at start up and come down to 30-40 psi once at op-temp. I would suspect the oil pressure sending unit or sensor to be faulty at start up or something weird is up with the electrical connection to it. Do you have full cluster package or idiot lights?

 

Rear XJ flares do not fit unless you do some good split down the middle cutting and bonding the complete halves to make a whole MJ rear flare. Time consuming and costly but worth it if you can't find original flares.

I have all the oil pressure I need, As you said. 60 cold, 30 hot.  just not when cranking, as with most motors... you’d need a pre- Oiler for that. It’s that slight rattle for maybe 1/2 to 1 second on its way to 3000 after sitting for a few days I don’t like. That’s why I’d like to try to keep the rpm flair up to a minimum. 

[eaglescout526]

5 minutes ago, Comanche1 said:

I have all the oil pressure I need, As you said. 60 cold, 30 hot.  just not when cranking, as with most motors... you’d need a pre- Oiler for that. It’s that slight rattle for maybe 1/2 to 1 second on its way to 3000 after sitting for a few days I don’t like. That’s why I’d like to try to keep the rpm flair up to a minimum. 

 

Couple questions. Do you have a mechanical gauge hooked up to where the sending unit or sensor is? Or is this coming from the cluster? If you have a cluster, Renix does a self test of the gauges that start from zero and peg out and come to the reading from the sensor as I'm sure you know with your experience.

Now when you say rattle from the engine, do you know where the rattle comes from in the engine/engine bay? My guess is something in the bay is loose and hitting against something.

 

Unfortunately how Renix runs the motor at start up is to run it at 3000 to get the oil flowing, depending on outside temp the high revs will help heat the air and the alt charging the battery. Theres not a whole lot of ways to stop that unless you start the truck every day and your RPMs could be lower at start up. I know mine will get close to 3000 on the first start up of the day. But if she sits for a couple days ill see 3k at start up.

[Comanche1]

1 minute ago, eaglescout526 said:

 

Couple questions. Do you have a mechanical gauge hooked up to where the sending unit or sensor is? Or is this coming from the cluster? If you have a cluster, Renix does a self test of the gauges that start from zero and peg out and come to the reading from the sensor as I'm sure you know with your experience.

Now when you say rattle from the engine, do you know where the rattle comes from in the engine/engine bay? My guess is something in the bay is loose and hitting against something.

 

Unfortunately how Renix runs the motor at start up is to run it at 3000 to get the oil flowing, depending on outside temp the high revs will help heat the air and the alt charging the battery. Theres not a whole lot of ways to stop that unless you start the truck every day and your RPMs could be lower at start up. I know mine will get close to 3000 on the first start up of the day. But if she sits for a couple days ill see 3k at start up.

I have absolutely no oil pressure concerns.  Just that, possibly bottom end, 1/2 second rattle when cold.  Maybe I’m just too Anal about my engines. 

[eaglescout526]

4 minutes ago, Comanche1 said:

I have absolutely no oil pressure concerns.  Just that, possibly bottom end, 1/2 second rattle when cold.  Maybe I’m just too Anal about my engines. 

 

You know what I bet that rattle is? If you go under the engine and look at your exhaust pipe at the end of the oil pan is a clamp probably free hanging, see if that's your possible rattle.

[Comanche1]

59 minutes ago, eaglescout526 said:

 

You know what I bet that rattle is? If you go under the engine and look at your exhaust pipe at the end of the oil pan is a clamp probably free hanging, see if that's your possible rattle.

Exhaust is perfect as is the rest of the mechanical throughout, even a new cat.converter. Driving me nuts. 

[Comanche1]

Really appreciate your input. Keep it coming 

[eaglescout526]

1 minute ago, Comanche1 said:

Exhaust is perfect as is the rest of the mechanical throughout, even a new cat.converter. Driving me nuts. 

 

Right I get that but if you havent replaced the down pipe of the exhaust, you might have this clamp or ring on the pipe still:

 

This thing used to rattle a lot for me an I would hear it at start up and driving. Replaced all bushings and havent heard this guy move around since.

[Comanche1]

Yep. It’s all tight too. 

[Ωhm]

Try disconnecting the new ISCM. This will make for longer CRANK time, maybe allowing extra time for oil pressure to increase. You may have to work the throttle with your foot when cold.

[Comanche1]

Really appreciate your input 

[Comanche1]

6 hours ago, Ωhm said:

Try disconnecting the new ISCM. This will make for longer CRANK time, maybe allowing extra time for oil pressure to increase. You may have to work the throttle with your foot when cold.

I’ll give it a try

[Eagle]

17 hours ago, rylee144 said:

Google says yes

 

Those are for the XJ. The front flares are the same. The MJ rear flares are NOT the same as XJ rear flares.