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97 OBS low power at WOT

68K views 271 replies 24 participants last post by  Airstreamer67 
#1 ·
Hey all, my 97 is completely stock shy of a full exhaust 3 inch down pipe and 5 inch out the back no cat no muffler and a clean new filter and A BRAND NEW TURBO. I bought the truck as she sits with 100550 miles on and clean as a whistle. I'm a technician and I have a snap on Solus Ultra so I can monitor everything the truck sees. My complaint is the truck accelerates normal as long I stay no more than about 1/4 throttle if I go WOT the truck drops gears as it should and the turbo screams but I go no where. Now I know everyone will just to trans shifting but this isn't the problem as the rims don't rise, they rise initially when I downshift but even in direct drive my rpms rise slowly as the truck slowly accelerates. Now I have no faults at all, except for P1111 for system pass.
I have verified correct operation of the EBPV and it moves free
I measured boost at the map sensor and had a max reading of 8psi WOT
I then under WOT manually applied vacuum to the map sensor and the the truck made no additional power, shook a bit and made no smoke.
The truck has never smoked any color.
As I said before this is a brand new turbo so there is no play in the wheels

So here's my questions:
What readings should I see from the map under acceleration
What should I see from EBPV
If the ebpv tube is clogged will this cause faults?
What should my fuel pressure be under wot, maintain 50-60psi?

I have no soot build up anywhere its clean as a whistle under there but If I were to smoke the intake system where would be a good place to do so? Straight in the intake hose?

Any other ideas?

Thank you all.
 
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#2 ·
Can you monitor the MAP signal on your Solus and see what the boost is from a mechanical gauge to correlate the two? You could always electrically disconnect the MAP and see if it is better running on default values. Fuel Pressure at WOT should be 30-60 psi. The EBPV tube is not hard to remove, so maybe check and clean if necessary (don't forget the sensor fitting and sensor). Cheers!
 
#3 ·
My truck acted alot like yours is a while ago and it turned out the hose going to the map sensor was leaking and not reading right. Check your hose to the map sensor and maybe unplug the map sensor to see if it runs better without it.
 
#4 ·
Pressurize the system and check for boost leaks. Make sure you take off the CCV and plug the hole in the intake tube. I made this to check for leaks



 
#5 ·
OK, got in to work a few hours early at 5 am and ran some tests.
Ran a cylinder contribution test: PASS
Buzz test: All 8 injectors sound the same... PASS
Solus offers a expected range that everything should be in and every monitor is 100% in
line with what is expected.
Fuel pressure at idle is 50-60 psi bouncing between the 2
Fuel pressure at WOT seizes between 30-60 psi but at higher RPM`s it levels out to 50-60
Next i smoked the intake with an actual smoke machine and found 0 leaks in the intake, through the map sensor hose, the up-pipes everything is solid...

annndd theeeeen

I noticed a little hose at the bottom of my fuel filter housing then goes from the front of engine to fuel filter housing that was not connected. I have no idea what this is for since there was no fuel leaking but I plugged it back in and my results... Nothing changed! lol
Maybe this is just how these trucks run I mean like I said im completely stock shy of opening up the intake hose and exhaust. No chip, no injectors, no trans modifiers. My problem is I work on BMW and I get in M3`s and do 0-100 in stupid fast then I get in the ole 250 and she feels slow... So it could certainly be psychological but I cant help but feel like 8psi at WOT is just LOW. Am I crazy? I understand power takes money and thats no issue I just want to be 100% sure everything is as it should be before I start adding power
 
#7 ·
oh ok thank you... Pulled this off of all data...

ok turns out i cnat copy and [paste from all data... moral here is alldata says at 2500-3000 RPM while t-ed in on map sensor line. " If boost pressure us 15.5 (90kPa) or more, boost level is ok. So theres definantly something peculiar happening im almost half of that.
 
#12 ·
So, have you checked to see how it runs with the MAP electrically disconnected? It will set a CEL, but you should be able to clear it. You might also check for any exhaust leaks at the manifolds and uppipes. Cheers!
 
#13 ·
Yea i disconnected it, set the CEL and ran it with no change. I smoked the turbos, intake and uppipes with no leaks found.

ICP pressure at idle is 584.8
IPR Duty cycle at idle is 13%

ICP Pressure at WOT is 1621.8
IPR Duty cycle at WOT is 35%

EBP at isle is 16
EBP at WOT is about 21
 
#14 ·
Icp under wide open throttle should at least be between 2500 and 3000. You said you ran it wi MAP unplugged, you did drive it while unplugged right? At idle, unplugging map won't make a difference except throwing a cel. Try also unpluging the icp sensor (driver side, top towars front of truck) drive it while its unplugged (seperatly from map) too.
 
#15 ·
Oh, and unplugging icp sensor will also throw a cel
 
#16 ·
Also, get under truck, and check and make sure none of the exhaust manifold bolts are broken. Rear driverside is know for breaking at head of bolt. And have you tried applying pressure to the system instead of smoke? Never used smoke, so just unsure if that pressurizes the system or not.
 
#17 ·
And you say truck drives normal at or under 1/4 throttle, what arr your readings at a non WOT (under 1/4 throttle) acceleration?
 
#18 ·
You didn't specify if you plugged off the CCV hole.. I would use a air compressor to pressurize the system and check for leaks. Especially around the intake plenums .
 
#19 ·
Yes every test I did was performed while driving the truck unless otherwise noted

I will have to get you those readings for 1/4 throttle acceleration

Smoke test pressurizes the system to about 10 PSI... This too low?
Yes CCVV was disconnected and plugged off

No exhaust bolts are broken

I did not get a chance to the run the tests I wanted to this morning as one of my guys did not show up. So it will be done tonight after work.
 
#20 ·
I would think testing around 20-22 psi would find smaller leaks anyway
 
#23 ·
Any improvements on the 97 ? I have a 96 with similar issues and found when I run a KOER scan with Auto Engunity I get no code but the truck seems to run normal until I shut it off.I have not yet found the cause of this problem as my laptop had a run in with the concrete. Just thought this my give you another angle to try. If you can find someone local with AE.
 
#24 ·
Are there anythings that can influence the HPOP output? Ive confirmed there are no oil leaks in the valley at idle. And no new updates. I do not have a AE but im using a snap-on Solus Ultra and it def gets the job done.

Are there any rebuild kits for the HPOP?
 
#25 ·
Your oil pressure from the HPOP is low, it means the pump is making pressure but there is a leak somewhere (don't think this is it) or the pump is worn out, means you can't achieve the proper volume and pressure at the higher RPMs.
You system should hold 2500 psi at WOT. The low boost pressure is indicating the same thing, without proper fuel delivery the turbo can't spool up.
The pump probably needs to be replaced.
I used an Adrenalin HPOP on mine, they work well, you could get a 17 degree SD pump, or any other pump.

Jim
 
#26 ·
1. Change your oil and filter, if the oil is of poor quality or old it can foam which can cause run issues. I use Delo 15-40 and NAPA gold filters, others have their favorite.
2. Pull the plug on your HPOP reservoir and inspect it is full, within 1 to 1/2 inch of top.
3. Remove your valve covers, inspect the amount of oil coming out of the discharge horns from the injectors, you are looking for an injector that is flowing a larger volume of oil than the others, you could be bleeding off the system with a bad injector. I don't think this is it but hay.
4. The ICP or IPR could be bad, it is also possible you have a bad o ring in the IPR check it out, replace them if you can.
5. Pull a plug at the front of the engine, the ICP would be a good spot, see if there is air in the rail, it should be full of oil.
6. If none of this helps, replace your pump.

Jim
 
#27 ·
jake2far...

Since this has began ive changed the oil and filter as well as fuel filter and cleaned the screen then performed the ipr mod. I use all OEM with mopar 15w-40 oil. Helped some but ultimately no difference.

I will check the level of the HPOP reservoir tonight

As for the injectors ive performed the cylinder contribution test as well as the buzz test.
ive also performed an injector balance test while watching with my fuel pressure gauge and all injectors passed all 3 tests.

O-ring in the IPR is a good idea and I will certainly be checking that however I feel like if that were the case then this would not be a concern that appeared only at WOT, and I would have hard start issues or rough idle or maybe smoke. But I have none of these symptoms, truck runs like a top just doesnt do it very quickly.

I will remove the ICP tonight as well and check on the air situation

Ultimately though I feel that your number 6 may be my culprit here. It is the logical choice unfortunantly. Now im researching which direction I want to go in the HPOP world.
 
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