LOST JEEPS :: View topic - My jeep is slow

Geordi,

We will assume your vehicle is fairly stock. It sounds like the EGR flow is having trouble reaching the set point air mass. In light to normal acceleration your vehicle may be overcompensating for some sort of restriction in the EGR system. During the accel the EGR will keep commanding further open and then the FCV is start closing to drive more EGR, but this limits the allowable boost and ends up leading to higher levels of smoke and lackluster response. Once you push the pedal deep enough, the air mass setpoint will increase to a point where less EGR is demanded and the FCV will open and EGR close, then you get a rush of performance.

If you can record the following parameters, we could check into it: air mass, air mass setpoint, fuel quantity, boost, rpm, vehicle speed, intake temp, coolant temp, turbo duty cycle%, FCV duty cycle% and rail pressure. Your system may not be able to record all of these values, but we will take what we can get. Thanks.

Mackruss,

The calibration and diagnostics are different with your vehicle since it was certified to the European emission standards and not the US. Do you even have a CEL light with the EGR blocked and FCV unplugged? In your situation, if there is no CEL the fuel economy should be better than stock and less lag from a launch. Your engine mounts might fail sooner than other KJs due to more mount excusion when the engine is turned off since the FCV is not working.

Thanks for the hijack

. I'm going to head out to the garage and scratch my head for a few hours.

Thanks for the hijack

. I'm going to head out to the garage and scratch my head for a few hours.

This sensor poses some unresolved issues. The parts fische does not show this sensor's part number. In the diagnostics it is labeled intake pressure sensor, it almost seems as if Chrysler forgot about it. The signal range is a 0-5 Volt with 0.5volt = 100 millibar and 4.5volt = 1200 millibar. Limp-home is the default reaction with a failed sensor and the CEL is on.

The sensor runs a diagnostic check with the atmospheric pressure sensor at idle and if the comparison is out of range, limp-home mode will be initiated. If the range is valid, the sensor should have no impact on performance. Your results are different from what we expected. The next couple of days we will perform some tests with the sensor to better determine all the potential effects of a bad sensor.

Author:	bigcoupee [ Tue Oct 06, 2009 1:39 am ]
Post subject:	My jeep is slow
I have a tough time getting up to highway speeds or past 3000rpm. Kinda sounds like the wastegate is stuck open, but i still can hear the turbo whistle. No smoke on acceleration, and can't find any leaks in the turbo hoses . Im getting P00112 INTAKE AIR TEMPERATURE SENSOR CIRCUIT LOW and P1189. Air filter is new, fuel filter new, boost pressure sensor clean. Maybe a faulty boost pressure sensor? anyone have the price on one? thx

Author:	Joe Romas [ Tue Oct 06, 2009 7:55 am ]
Post subject:
We don't have a waste gate We have a Garret Varriable Nozzle Turbo (VNT) turbo. Did you clean the MAP sensor that is on the top of the intake manifold under the plastic tray with wires in it that needs to be move

Author:	linewarbr [ Tue Oct 06, 2009 7:59 am ]
Post subject:
Isn't the air intake temperature sensor the little Mercedes-Benz sensor on the engine side of the airbox?

Author:	GreenDieselEngineering [ Tue Oct 06, 2009 10:17 am ]
Post subject:
Definitely check the air intake temp sensor on the side of the air box, it is very close to the turbo outlet hose. The connector retention clip on that sensor is very weak and tends to fail. Hopefully you just have a loose connection.

Author:	geordi [ Tue Oct 06, 2009 11:05 pm ]
Post subject:
Boost pressure sensor is $180 at the stealership, But I would be happy to sell you the new one that I bought; for $120 shipped. I thought I had a buggy sensor b/c my CRD has been behaving strangely, but the sensor didn't change anything. Problem is, no return on any electrical part to the dealer. Green Diesel, maybe you can offer some insight to this: Under low RPM operation and usually just following a braking event such as a random slowdown of traffic or rolling through a turn... When I get back on the go-pedal, the boost rises relatively slowly on my gauge, the EGT also slowly increases... But the CRD is not accelerating strongly at all. Instead, it feels like it is bogging down and it blows HUGE clouds of smoke until I almost floor it. Then like flipping a lightswitch, it suddenly applies the power to the ground and accelerates strongly. This is 100% reproducible by braking from 60 down to 30, then getting back onto the go-pedal. I'd be happy to send you a CSV map from the Autoenginuity scanner, just tell me what sensors to map. I suspected the boost sensor, but that obviously isn't the problem. I do think that this is electronic though, for the repeatability and the fact that when it "fixes" it is just like my VW TDI when the MAF was bad - The car would be trying to figure out the erroneous sensor signal, while performing in exactly the same way - Simply not accelerating at all (no smoke from the VW tho) then it would "give up" and go to a default number, and the car would accelerate sharply when the computer changed the data. Thanks for any insight.

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Author:	GreenDieselEngineering [ Wed Oct 07, 2009 7:01 am ]
Post subject:
Geordi, We will assume your vehicle is fairly stock. It sounds like the EGR flow is having trouble reaching the set point air mass. In light to normal acceleration your vehicle may be overcompensating for some sort of restriction in the EGR system. During the accel the EGR will keep commanding further open and then the FCV is start closing to drive more EGR, but this limits the allowable boost and ends up leading to higher levels of smoke and lackluster response. Once you push the pedal deep enough, the air mass setpoint will increase to a point where less EGR is demanded and the FCV will open and EGR close, then you get a rush of performance. If you can record the following parameters, we could check into it: air mass, air mass setpoint, fuel quantity, boost, rpm, vehicle speed, intake temp, coolant temp, turbo duty cycle%, FCV duty cycle% and rail pressure. Your system may not be able to record all of these values, but we will take what we can get. Thanks.

Author:	mackruss [ Wed Oct 07, 2009 7:27 am ]
Post subject:
GreenDieselEngineering wrote: Geordi, We will assume your vehicle is fairly stock. It sounds like the EGR flow is having trouble reaching the set point air mass. In light to normal acceleration your vehicle may be overcompensating for some sort of restriction in the EGR system. During the accel the EGR will keep commanding further open and then the FCV is start closing to drive more EGR, but this limits the allowable boost and ends up leading to higher levels of smoke and lackluster response. Once you push the pedal deep enough, the air mass setpoint will increase to a point where less EGR is demanded and the FCV will open and EGR close, then you get a rush of performance. If you can record the following parameters, we could check into it: air mass, air mass setpoint, fuel quantity, boost, rpm, vehicle speed, intake temp, coolant temp, turbo duty cycle%, FCV duty cycle% and rail pressure. Your system may not be able to record all of these values, but we will take what we can get. Thanks. Mr GDE What happens with what you described above if the EGRis blocked off and the FCV is open as is the case with my CRD?

Author:	mackruss [ Wed Oct 07, 2009 10:40 am ]
Post subject:
GreenDieselEngineering wrote: Mackruss, The calibration and diagnostics are different with your vehicle since it was certified to the European emission standards and not the US. Do you even have a CEL light with the EGR blocked and FCV unplugged? In your situation, if there is no CEL the fuel economy should be better than stock and less lag from a launch. Your engine mounts might fail sooner than other KJs due to more mount excusion when the engine is turned off since the FCV is not working. Thanks, no I didn't get a CEL after having done the mod but the shutdown is a bit tough on the engine mounts. What happens if i leave the EGR blocked off but re-fit the FC valve

Author:	mackruss [ Wed Oct 07, 2009 12:14 pm ]
Post subject:
bigcoupee wrote: Thanks for the hijack . I'm going to head out to the garage and scratch my head for a few hours. Sorry ,my bad

Author:	bigcoupee [ Wed Oct 07, 2009 12:15 pm ]
Post subject:
Thanks for the hijack . I'm going to head out to the garage and scratch my head for a few hours.

Author:	linewarbr [ Wed Oct 07, 2009 2:04 pm ]
Post subject:
bigcoupee wrote: Thanks for the hijack . I'm going to head out to the garage and scratch my head for a few hours. Did you get a chance to look at the air temp sensor? It's a Mercedes-Benz sensor on the front-engine-side of the air box. Easy to get to; if you did the V6 airbox mod you had to disconnect it when you changed out the box.

Author:	bigcoupee [ Wed Oct 07, 2009 7:33 pm ]
Post subject:
Yep disconnected intake temp sensor, easiest and cheapest fix i've ever had. Thanks a million!

Author:	mackruss [ Thu Oct 08, 2009 4:08 am ]
Post subject:
bigcoupee - can I carry on hijacking your thread now that your problem is solved To the very helpful GDE folk; Thanks for the response to my FCV and EGR question. With the experience that you guys have now with the CRD's, is the EGR so much of a nuisance and does it have such an effect on the performance / longevitiy of the motor as has been discussed on this forum. I'm speaking for myself here only, should i run the risk of having to replace the engine mounts prematurely and risk damaging something else with the rough shutdowns due to a FCV mod and a blocked EGR valve where the perceived benefit of having done the mod in the first place may not be all that beneficial. Added to this, it appears that the Euro / Export models are spec'd differently with their emission management than the US models. This is evident with no CEL after i did the EGR plate and FCV mod so I'm wondering if my EGR is as active as that of the US models and if not, should I not revert to stock setup and smoother shutdowns. Thanks in advance.

Author:	kb61751 [ Fri Oct 09, 2009 1:36 pm ]
Post subject:
Try to give it a little throttle when you shut it off, makes mine smooth.

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Author:	geordi [ Fri Feb 12, 2010 11:11 pm ]
Post subject:	Re: My jeep is slow
Zombie thread - I have finally found my solution (I think) and want to make sure people know about it. The problems I have been experiencing seem to be caused by the Mercedes Logo sensor on the side of the airbox. I unplugged that as a test, and the performance of the CRD WENT UP at low speeds. Yea, it was in limp mode, but HOW BAD has the performance been if limp mode is BETTER than what I had? Does anyone have the correct part number for that sensor? I tried cleaning mine... And it responded with better performance for a bit, now is dragging down the engine performance again. So this certainly seems to be the source of my annoyances. I've seen descriptions here that it is all (or one) of the following: Air intake pressure (like a barometer?) Air intake temperature Anybody know what the range of this thing is? Could I wire in a variable resistor to this, to up the performance or replace it's function? GDE? Thoughts? What exactly does this control in the computer's power map?

Author:	GreenDieselEngineering [ Sat Feb 13, 2010 12:21 pm ]
Post subject:	Re: My jeep is slow
This sensor poses some unresolved issues. The parts fische does not show this sensor's part number. In the diagnostics it is labeled intake pressure sensor, it almost seems as if Chrysler forgot about it. The signal range is a 0-5 Volt with 0.5volt = 100 millibar and 4.5volt = 1200 millibar. Limp-home is the default reaction with a failed sensor and the CEL is on. The sensor runs a diagnostic check with the atmospheric pressure sensor at idle and if the comparison is out of range, limp-home mode will be initiated. If the range is valid, the sensor should have no impact on performance. Your results are different from what we expected. The next couple of days we will perform some tests with the sensor to better determine all the potential effects of a bad sensor.

Author:	Goglio704 [ Sat Feb 13, 2010 1:40 pm ]
Post subject:	Re: My jeep is slow
I may be wrong, but I think people have been getting the sensor on the side of the airbox when they thought they were ordering the MAP sensor. Maybe somebody will chime in.

Author:	geordi [ Sat Feb 13, 2010 2:28 pm ]
Post subject:	Re: My jeep is slow
GreenDieselEngineering wrote: This sensor poses some unresolved issues. The parts fische does not show this sensor's part number. In the diagnostics it is labeled intake pressure sensor, it almost seems as if Chrysler forgot about it. The signal range is a 0-5 Volt with 0.5volt = 100 millibar and 4.5volt = 1200 millibar. Limp-home is the default reaction with a failed sensor and the CEL is on. The sensor runs a diagnostic check with the atmospheric pressure sensor at idle and if the comparison is out of range, limp-home mode will be initiated. If the range is valid, the sensor should have no impact on performance. Your results are different from what we expected. The next couple of days we will perform some tests with the sensor to better determine all the potential effects of a bad sensor. Yea, I wouldn't have suspected this thing either, since like on my Jetta when the MAF was failing... No codes in the computer, just an "I'm gonna get you killed b/c there is no power when you need it" kinda responsiveness. What I was shocked about was the result from just unplugging the dang thing while filling up a couple days ago. I had pulled into the station with a mostly-cold engine (running only about 4 minutes from stone cold, and only low speed) and just decided to give it a test. Pulling OUT of the station, even just away from the pumps, the CRD felt like I had removed 1000# from the frame. With a light-to-moderate throttle, it felt like it actually WANTED to accelerate, and could have chirped my studded snows if I had asked it. I'm interested in experimenting with some resistor replacements for this, I think that might be a quick solution for this sensor, especially if Mopar has basically disavowed it's existence. Replacement with a resistor would then always give a "proper" response to the fuel map... And people won't be looking for a $300 sensor that doesn't exist at a dealer. It would seem to me that this is yet another example of "too many computers" in this vehicle. Checking at idle... That makes sense, the CRD is always pulling it's "overfueling and smoking with moderate-to-heavy-throttle" right after being completely off the throttle, and sub-40mph speeds. So the engine COULD be dropping to idle then.