Idling blues

[Mopar-muscle]

yes marco is right , i was just about to post that .

also on injectors , when you did the test how did it sound between cylinders when you cycled the injectors ? i had a problem like that with 275's , 2 bad cylinders , they sounded very different than the others . i took the injectors to the bosch shop i got them from , when they tested them by the BOOK they were within spec , but when they cracked them slowly , much like idling , there were two that were marginal , i never told them which , but i numbered the injectors and the 2 bad ones were the bad cylinders that were found when ted j. ran the test for me .

 

[Vaughn MacKenzie]

I didn't think Jack's ECM would work on mine but he thought it would. It was a good idea anyway.

When I played with the scan tool the cylinders all sounded the same. But the scan tool made the engine surge erratically during the test routine so it was hard to tell. If I'd been thinking I would have asked the tech at Campbell to run an injector shutoff test with their equipment.

Marco, if my truck still doesn't idle smooth after a reflash, what are the odds it is an ECM problem? What about the CAN-bus electronics?? Someone posted about shadow pulses or spikes or something to that effect which can unsettle the electronics between the ECM and injection pump. What do you think??

If I totally ruled out electronics and still had a problem, then balanced and flowed DD3s should eliminate my problem #ad


Thanks again guys for your input.

Vaughn

 

[Vaughn MacKenzie]

UPDATE

Well how about an update on my irritating, annoying idle/drivability porblems? Since my last post I have:



Added DD2 injectors (about 8000 miles ago)

New set of injector tubes (tonight)



Affect on idle? Slighty worse So injectors and tubes are ruled out. Lawrence at DD suspected the tubes since he sees a fair number of bad ones when installing injectors. It was a good idea but that wasn't it.



I am pretty certain there is a noisy signal from the tach sensor, MAP, APPS, temp, or whatever, that is disrupting the electron harmony of the ECM. Tonight on a test run I had to wait for a train, so while sitting there I revved it to a bunch of different RPMs to see how it behaved. Well at some speeds it is pretty smooth, at others the truck jiggles because one cylinder isn't delivering the same power, at 2100 it surges erratically (it surges at a lot of points but is worst around 2100).



To recap, I have:



Checked lift pump pressures @ WOT--good

Checked for leaks--no trouble hitting 35psi boost

Valve Adjustment--only 3 were off slightly (. 002" max)

Attached DRB scan tool--can't see any anomolies

Reflashed ECM--smoothed tach a bit, no help otherwise

Cleaned/swapped around injector tubes--no help

Installed DD2s--no help

Replaced injector tubes--no help

--Another note, cruise control is very erratic, like it is calibrated for about 150hp less (or 2000lb heavier truck). Also when cruising along I can feel a constant slight power surge/drop like a gasser with inconsistent A/F ratio.



I am not a happy camper tonight and am about ready to hand my truck over to anyone I think can fix it once and for all, no matter what the cost. It drives me nuts when something is not right, and all efforts to correct it are in vain. I am picky about how stuff runs and expect it to run right. I am open to suggestions on where to take it. Piers already went on a test run with me but it was a model child when he was on board, dang truck (that's the solution. . . take Piers with me EVERYWHERE! )



Anyway I am thinking of taking it to the Power Shop or similar such place that is as good at troubleshooting/repairing these CTDs as they are BOMBing them.



Vaughn

 

[Marco]

Vaughn,

I wish I could help you. The problem is, I'm here, You're THERE...



Do you have a buddy with an smooth idling ETH? Try to swap the ECM and see what happens. IF your problem is electronics related then you should start from there. Next I would check the complete ECM harness. If also that doesn't help then I would try a new CPS.

Just a few thought's.

Marco

 

[Marco]

Sorry,

another one! The IAT! Seems to quieten the idle... .

Marco

 

[Vaughn MacKenzie]

Marco, I think I'm going to pull out the oscilloscope and the schematics in the service manual and start looking at all the signals, starting with the IAT.



If I were to swap ECMs, would it mess anyting up that is in "memory" or whatever? Is it simply a matter of disconnecting the batteries then unbolting/unplugging it?



Vaughn

 

[Marco]

Vaughn,

Nothing will happen to the files stored into the ECM's. You not even need to disconnect the batteries to swap the ECM's.



The scope will not help you much. With the scope you could find a completly bad sensor, not one that's working rather good like the one you're supposedly searching for.



Marco

 

[Vaughn MacKenzie]

Any NW BOMBer volunteers?

Well are any of you NW BOMBers with a smooth-idling ETH willing to do a ECM test swap with me the next time we have one of our BOMBfests??

 

[Bob Wagner]

these guys never throw parts at the problem

Vaughn the powershop advertises on the KVI radio auto repair program and they never advise throwing parts at the problem.



Shoot em an email @ -- email address removed --



what the hell its free advice from a couple of top notch mechanics

 

[MikeR]

The only thing left is your injector pump. The Powershop has changed many of these,and I'm pretty sure they may suggest it.

Too bad you and Evan didn't swap ECM's to verify that last time he was there.



-Mike

 

[Evan A. Beck]

Very strange problem Vaughn...



Does it stumble or run rough while driving? At all? And if so, is it confined toa certain RPM range?



We had a truck with this very problem about 6 months ago... Turned out to be an injector pump. The guy had a tank of bad fuel that killed the pump. Truck would run real nice, but had a miss at around 1,800-1,900 RPM. I switched the stock injectors back in it, and it made no difference--still ran rough, at the same RPM range. Only thing left to change, was the injector pump. Cured the problem, truck ran great--no missing or rough running. I put the Dr. P injectors back in it, and the thing hauled a$$.



How did your truck run with a VA? Was it smooth? Is your problem more prominent when cold or warm? Also, how did it run with the EZ installed? Be specific with details... We'll get to the bottom of this...



Seems like evrything is pointing to the VP44, but we can try a few other things first.



--Try all the add-on plug in boxes. See what happens...

--Want to try swapping in my stock injectors, and see if it makes a difference?

--Check the MAP and IAT sensors.

--Check the cam sensor.



Keep us posted...

 

[John]

Hey Evan, I remeber you working on that bite-in-the-a$$ Ram. Is it still running OK?

 

[Swayse]

Vaughn,



Mine is doing almost the same thing yours is doing, (my user name used to be Swayse), but mine is a ETC. After DD1 injectors and a EZ box cruise works like crap, unuseable. It's real hard to listen to my brother in law's truck, it idles so smooth. I'm thinking of replacing the AIT or ATI, whatever it's called and see if it will help.



Please post if you find a solution, and I will do the same.

 

[Alan Reagan]

Peter, You mean the IAT (Intake Air Temperature) sensor? Don't know if that will help you or not on the rough idle. Seems to be helping alot on adding proper fuel for air temp tho.

 

[Vaughn MacKenzie]

Man look at all the input I'm getting!



Evan, let me tell you as much as I can:



--When I had the VA on or EZ it did a couple slight hiccups, mostly with the EZ.

--It is rougher when warmed up, the hotter, the worse. But, it still isn't 100% smooth when cold.

--Not only is the idle a bit rough, but power surges slightly when driving, and when free-revving the engine surges/gallops around 2100rpm "vrum vrum vrum" rapidly.

--It's not the injectors, it did the same thing with stock, RVs and now DD2 injectors.

--Pretty sure it's not the injector tubes.

--It hasn't had a smooth idle since new, I wish I'd gotten to the bottom of it immediately but was hesitant to go to the dealer, and hoped it would go away once broken in. It was worse during the first 500 miles than now.

--The surging problem was not there from day one, it started suddenly around 18,000 miles.

--I have no MPG of power problems at all, runs great otherwise. Got 23 on the last tank.

--I disconnected the batteries overnight but that had no effect.

--The ECM seems hypersensitive, any tiny increase in load and the engine overreacts (engaging A/C, cruise control, etc. ) Adding DD2s made that worse.



This is sort of a problem that really isn't that bad, many people would never notice it or think anything is wrong, but it is there and it's annoying  Like Peter mentioned, I've ridden in several trucks and they all idle much smoother than mine, though MikeR's sorta idles like mine



Is there any way to check out the MAP, IAT, & cam sensors?? Without buying new ones?? I would definitely start with the cheap/easy stuff, and swapping ECMs, before jumping into replacing the injection pump.



Evan, if the injection pump is defective, any way it can be done warranty through your shop?



Thanks again everyone. Vaughn

 

[Alan Reagan]

The IAT will vary resistance.



32*F will get you about 40Kohms , 81*F will do about 6. 87K, and 130*F is about 4. 0K.



The MAP is a little more difficult since you are measuring Air pressue. I can't remember which way the voltage goes but it's range is 2. 5V to 4. 5V (I believe) with 4. 5 being max at sea level with the lower voltage at higher altitudes (somebody help me out here). It's in the service manual but I don't have it here.



Same problem with the camshaft position sensor. I believe that's a Hall effect device that's hard to tshoot.



If the Camshaft PS was faulty, I think you would have more of a tachometer associated with the idle problem.

 

[Marco]

The MAP sensor should give something like 0. 55-0. 6 Volt output at idle. As the pressure increases the Voltage raises. Altough we're dealing with a strange problem here, I don't think it could be caused by the MAP.

Not even the NASA could figure out a bad CPS with a scope. Only way to find out is to change that thing.



I have another thought for you Vaughn. Pin # 11 @ the ECM is the ground for all the ECM's sensors (except CPS). Once I had forgotten to connect wire # 11. The engine would idle @1200 RPM ( Kinda cheapo fast idler) also idle was VERY rough. Start to check all the connectors that have to deal with the senors ground...



Sure there are endless possibilities on WHAT causes that problem,

somewhere you have to start.

Marco

 

[Swayse]

Yeah, IAT, Intake Air Temperture. I knew it was something like that. With DD3 on a hot day, it's sounds bad. I even sent back my first set of DD3 thinking there was something wrong with the injectors. Put in the second set, same thing. Now I'm running DD1's, not as bad but still troubles me.



I bet I'll be able to hear it more now after this post coming up again. Good thing I can't drive my truck right now, or it would drive me nuts. I'm suffering from withdrawl, I haven't driven my truck in little over a day. I'm putting it my clutch, having the flywheel refaced and bored to 1. 380 for the new bushing right now. The flywheel should be ready in about 2 hours. It's hard to see the truck apart like that.

 

[Alan Reagan]

Vaughn, I just got off the phone with A&M Turbo (local Bosch shop). He said that a bad lift pump can/will cause the surging and can cause rough idle. The first thing I thought of on the surge was getting air in the system. That was one of the first questions he asked. Of course, with the VP44 you can't just snatch it off and put it on a machine like the P700. He said it would have to go back to Bosch. Now, I just changed my lift pump two weeks ago. Prior to the change, I was getting a surge during acceleration. That has disappeared. I did/do not have a rough idle or tach variance. I mentioned all you had done and he's down to lift pump, air getting in the system or the VP44 just from the conversation. Yeah, I know, that pretty well covers the entire fuel system.

 

[Vaughn MacKenzie]

Alan, I have thought of that too, but my lift pump pressure never drops below 6. 5psi @ WOT, and doesn't spike or pulse reading my mechanical gauge at the injection pump.



Marco, I am thinking it could be a poor connection somewhere, and engine vibration irritates it. I found the pinouts for the injection pump wiring so that is helpful.



The biggest thing I have working against me right now troubleshooting my truck-- The weather in SE Washington is competing with Phoenix & Las Vegas this week, it's not fun working on a truck in 100F+ weather. It was 93F by noon today .



Vaughn