You be the judge/jury - HPOP/ICP - which one is guilty? - Diesel Forum

bluenavigator · 08-28-2008, 03:04 AM

Somehow, I was so busy and didn't get chance to redo the diagnios on my truck. I had posted the issue on my truck. Armed with new oil pressure gauge, I pulled ICP out and put the oil pressure gauge in the ICP's hole. I changed the oil. The oil was ruined with brake fiuld that I accidently poured in the engine. I drained and left it draining all the day. The oil stopped dripping, leaving strange gummy oil - bad oil or that was result of adding brake fuild to the engine oil? I just hope that 1/2 cup of brake fuild doesn't have much effect on the engine. Anyway, I recharged the batteries since the truck wasn't started over 2 months. The engine started on first try, which is good news. I watched the high oil pressure gauge as I rev'd the engine. I recorded the results.

The results:

600 rpm - 600~650 PSI <--- idling speed
1000 rpm - 650~700 PSI
1500 rpm - 700 PSI steady
2000 rpm - 800 PSI steady
2500 rpm - 1100~1250 PSI (tried to keep engine reving steady)
3000 rpm - 1400 PSI (able to hold the engine reving steady)

Are the results good? The ICP is out of the engine and sitting on the work bench in my garage. Pretty much that it tells you that ICP isn't plugged in the system. Do I need to retest this with ICP out but plugged in the system? Let me know which part is the guilty party.

**action4478** · 08-28-2008, 09:18 AM

With the ICP out ,,the PCM has to guess what to tell the IPR to do,,,Put the sensor back in & use another port ....

MarkEkberg · 08-28-2008, 11:50 AM

If you are seeing low HPO is can be more than a IPR or HPOP.

Rarely do the HPOP go bad. They may get weak, but that is in the upper rpm's.

I agree with above statement. With the icp out the computer defaults to a specific psi in programing only. So it is basically guessing.

If you know someone with a scanner you can monitor the hpo while opening the ipr with a direct 12v signal. This will eliminate the ipr as a cause if the scanner sees the ipr fully open and there is a bunch of pressure.

If the IPR is stuck it could trick you.

What happened to me recently was a torn injector o-ring. I had one injector stealing the hpo from all the other injectors causing a no start, but it would start on ether. Many people knocked their heads against the wall on it. It was suggested here, but I discounted that due to the o-rings being replaced with-in 75K. Long story short pull a valve cover and see if your loosing alot of oil from one injector v/s the others.

bluenavigator · 08-28-2008, 12:30 PM

Put ICP back in and used next port after ICP port. Can see the difference. The results are different as I recorded them.

Results:

600 rpm - 500 PSI (started from cold)
1000 rpm - 1400 PSI
1500 rpm - 1400 PSI
2000 rpm - 1400 PSI
2500 rpm - 1500 PSI
3000 rpm - 1600 PSI

fall back to 600 rpm, it stays at 1400 PSI. As I rev'd all ranges, it only ranges from 1400 PSI to 1600 PSI. Back to idling, it could go back to 1100 PSI. Seem that it goes all over the place in range of 1000's PSI. So what does that tell you?

**action4478** · 08-28-2008, 12:46 PM

Quote:

Originally Posted by bluenavigator

Put ICP back in and used next port after ICP port. Can see the difference. The results are different as I recorded them.

Results:

600 rpm - 500 PSI (started from cold)
1000 rpm - 1400 PSI
1500 rpm - 1400 PSI
2000 rpm - 1400 PSI
2500 rpm - 1500 PSI
3000 rpm - 1600 PSI

fall back to 600 rpm, it stays at 1400 PSI. As I rev'd all ranges, it only ranges from 1400 PSI to 1600 PSI. Back to idling, it could go back to 1100 PSI. Seem that it goes all over the place in range of 1000's PSI. So what does that tell you?

Injectors may not need all the built up pressure ?..

What problem are you having?..

bluenavigator · 08-28-2008, 03:08 PM

The problem, that I am seeing on my truck, is the engine is running okay but I noticed once in while during driving or parking, the engine stumbles once or twice. The CEL is lit on.

How it happens - when I start my truck from cold, it would running fine but CEL light is on. Then couple minutes later, the engine seem to be missing or tried to die for a moment. I am talking about one second or two. It went back to running normal then CEL light went out. The problem disappeared on me. But when I drove down the road, it stumbled once again but CEL light didn't on at all. So I took it to the dealership to have it diagnoised. I don't know why they didn't tell me the code at all but gave me the printout. The paper just quoted "ICP Circuit Malfunction" and showed that ICP and ICP connector are recommended to be replaced. Might have more problems to uncover. I don't know anyone who has scanner/monitor to tell more than that. That's why I went to dealership in Hutto, Texas to get diagnois, which isn't much help at all. I don't know if IPR could cause this problem. I am trying to figure out what caused this short stumble ("shaking") engine.

**action4478** · 08-28-2008, 06:02 PM

The ICP sensor & the connector are a fairly cheap test you can do yourself ..

I see ICP's on E bay fairly cheap...

Yours may be leaking oil or corroded ,,,,

bluenavigator · 08-28-2008, 06:20 PM

Quote:

Originally Posted by action4478

The ICP sensor & the connector are a fairly cheap test you can do yourself ..

I see ICP's on E bay fairly cheap...

Yours may be leaking oil or corroded ,,,,

My ICP is leaking oil? I don't see any oil leak from that area. Think injectors are leaking oil to somewhere else? So pretty much that ICP is faulty?

**action4478** · 08-28-2008, 06:31 PM

Quote:

Originally Posted by bluenavigator

My ICP is leaking oil? I don't see any oil leak from that area. Think injectors are leaking oil to somewhere else? So pretty much that ICP is faulty?

Unplug the connector & look at it ,,,it should be dry....

A faulty ICP sensor can mimmic CPS symptoms ,,,

so can the small relays in the distribution box ....

bluenavigator · 08-29-2008, 02:34 AM

Quote:

Originally Posted by action4478

Unplug the connector & look at it ,,,it should be dry....

A faulty ICP sensor can mimmic CPS symptoms ,,,

so can the small relays in the distribution box ....

Checked ICP sensor and it is clean and dry. Will check relays in daytime. Are these relays in the cab or in engine area?

**action4478** · 08-29-2008, 09:16 AM

Quote:

Originally Posted by bluenavigator

Checked ICP sensor and it is clean and dry. Will check relays in daytime. Are these relays in the cab or in engine area?

The relays are under the hood ,,there are 5 slots ,,mine is only using 4

bluenavigator · 08-30-2008, 06:00 PM

Checked 4 relays, 5th one isn't used as there are no wiring to #5. I pulled all 4 of them and tested them. They are working fine. I noticed another 2 on side of that panel. Checked them in case. They are good, too. *scratching head*

bluenavigator · 09-03-2008, 12:02 AM

No more replies? Does that mean that my problem is very small that is neglicatable??? Or my problem is very difficult to diagnois, and better leave this problem to the experts?

Actually, it does bother me when I start and see CEL light on then go out every time. Also, I hate to see my engine shake so HARD momently, meaning piston heads could break at anytime, meaning replace the whole engine that I couldn't afford at all. 2000 bucks++ is out of my budget unless someone give me much better salary job.

MarkEkberg · 09-03-2008, 07:15 AM

Engine shaking badly? That is new. You were talking about hpo before.

You could have some burnt injector harnesses under the valve cover which is causing the computer to shut down the left or right bank.

**action4478** · 09-03-2008, 08:45 AM

Quote:

Originally Posted by bluenavigator

No more replies? Does that mean that my problem is very small that is neglicatable??? Or my problem is very difficult to diagnois, and better leave this problem to the experts?

Actually, it does bother me when I start and see CEL light on then go out every time. Also, I hate to see my engine shake so HARD momently, meaning piston heads could break at anytime, meaning replace the whole engine that I couldn't afford at all. 2000 bucks++ is out of my budget unless someone give me much better salary job.

The CEL will tell us where to look,,, IDM codes or not ...