Tiger Rag

A buddy of mine ordered new 100 hp injectors and I bought his rv275 injectors to put into my truck. We got the switch done with no issues. He shifted his into gear after we did his and it nearly stalled. We took it for a ride and doggone it is strong.....seems to run very smooth and powerful. We grabbed a bite to eat for dinner and got back into his truck and he shifted it into drive and it did stall this time. He started it let it warm up for several minutes and tried again and again and it continued to stall. It didn't do this when he had the rv275 injectors in his. Here is the info on his truck:

99 4x4 24v ctd. DTT auto transmission 89%, 355 rear end. Mad ECM, 100 hp injectors. I think that is pretty much it.

Any suggestions at to what the issues could be or a fix? His truck idles around 500 rpm I believe. He commented that my truck idled much higher at around 800 rpm. Don't know if this could be a factor or not. Clearly something isn't exactly right though. Suggestions, theorys, opinions and experience are greatly appreciated.

BTW, my truck runs great with the rv275's and the Edge Comp ! Slipped the clutch for the first time last night . Have to be careful with that. Guess South Bend will get a call from me before too long .

Thanks in advance, Matt

BigBlue

His truck in gear with the AC on should be around 700 or so. I have no idea how to adjust the idle on the 24v's but I have a feeling that it's in the ECM.

Tiger Rag

Well we were wondering if it could be the Mad ecm too. Dunno though.

His truck is an auto and mine is a 6spd. Didn't know if that was the reason for different idle speed?

We did a search and there was a thread suggesting you could adjust your idle by turning a torx screw in the APPS?

BigBlue

I did not know about the torx screw in the APPS. I'd be very careful fidling with that. APPS are not cheap to replace. There shouldn't be any difference between 6spd and auto. My roommate has a 6 spd and I've got an auto and we both idle around 750-800.

Don M

The MAD ECM would not be the issue. At least that is the last place I would look.

Typically, if you get a truck that has a hard time keeping idle or that dies when you shift it into gear from neutral after changing injectors; Two things that could be happening:

1) Tight TQ converter is putting extra load on the engine at idle.

2) The injectors pop pressure may be too high.

Even if the injectors are set perfectly on factory spec'd pop pressure you can get internal wear in the VP pump that will lower the idle injection pressure enough to cause this.
Or if the injectors were the "do it yourself" nozzles and the pressure was not set, the problem could be the pressure is just way out of spec on the high side.
Lower the pressure below factory spec by 10-15 BAR. This fixes nearly all problems related to low idle injection pressure.

The final thing can happen but is not related to the injectors pop pressure or converter is the connector tube could be not quite perfectly connected to the injector at the interface. Sometimes the install procedure can be followed again and the problem will go away. I like to remove the connector tubes and check for any signs of damage on their ends when I do this. 600 wet/dry sandpaper works good to clean up any rough spots. Be certain to clean the connector tubes real good before install after using the sandpaper use.

So, check the connector tubes and verify the pop pressure is set correctly if the injectors were the do it yourself things.

One trick that works sometimes is to just drive the truck a few days and see if it goes away. Sometimes a single injector that is set high might lower down some over time from minut wear during break in that helps the injector open easier.

HTH,

Don~

J BODY

I wouldn't fool with the torx screw on the APPS. You may mess up the idle validation.

Tiger Rag

Ok, here is an update after a long day yesterday........some of the day dynamatting my truck......well actually a dynamat alternative, Fatmat. I'll post results on that on another thread.

Between Don's suggestions and another knowledgeable friend that seemed to be on the same page as Don we made sure injectors lines were seated properly and made sure feed tubes weren't boogered up. We pulled the feed tubes and smoothed with some 600 grit emory paper and cleaned well as suggested to us. Truck still doing the same. We tried cracking injector lines to bleed air. Still no difference. The other thing suggested is to run them for a few days to see if they will seat themselves by the heating and contracting and clear the problem up. That is one of our upcoming steps now. I think the other thing we'll examine is the APPS. I guess the last resort will be to get new injectors to replace these. I guess the thing that is confusing is that the truck didn't do any of this with the tranny upgrade or the rv275's he had before.

Thanks Don and others for the suggestions, any further ideas are appreciated. Good info so far, we'll keep trying to troubleshoot. Hopefully we'll learn some good info that may help someone else down the road too.

Regards, Matt

AlpineRAM

Will the truck rev in neutral? I think that 500 rpm is much too low for idle speed.
I'd suggest not to touch the APPS! (Because as long as it's on the idle position the ECM should do the idle RPM on it's own- regardless of the APPS voltage- if you adjust it out of the proper voltage range you'll get some codes and if you turn it up too much the engine will never see idle anymore)
If possible try to pull codes (you'll need a scanner for that on the 99 IIRC)
How about the basic stuff like fuel pressure, fuel filter etc?

AlpineRAM

SmokeyBear

maybe an APPS reset is in order?

CTD2001

When my Bully Dog stage 5 went in my truck, i had a similar problem like the one you are having, the truck did not stall, but it sure felt/sounded like it was going to, it was probably as close to stalling as you could get with out it acutually stalling. I asked why it did that and i was told it was just the injectors. Well, case was that my Vp44 was about to crapp out on me. I had the code for the injector pump. Had the injector pump replaced and have not had the problem since then.

TORQUE

I wouldn't even try to mess with the APPS, as they are calibrated, and idle can't be changed,do reset instead. It could be fuel or trans related also. Did it start after one specific mod was done? Could be too tight of a converter, as mine did that when I had new trans done, they put 91%-1400 stall converter(instead of 89%-1750rpm stall). When it was changed out it was fine again. When I installed Don M's Mach 1.6's prior to doing trans, it never changed anything(except more power ). You'll just have to isolate which it is, APPS, fuel, or trans.

Big Deezul

it doesnt adjust the idle anyway...only the tps readings

500 rpm is super low for a 24v idle..It should be around 700-800

Tiger Rag

My mistake on the idle speed. We had a convesation and his is lower than mine, but I interpreted incorrectly. After examining what it really is, it is probably 700-750 give or take.....2nd mark above 500 rpm. Mine is on the 3rd.

We are going to attempt an APPS reset shortly to see what that does.

Torque, he has the 89%. It was done a few weeks ago, but no symtom like this then. This has occured after installing new 100hp injectors only.

Truck is running strong after it gets into gear......very strong!

TORQUE

Those 2 screws for idle and governed speed will not change if you try to adjust(DO NOT TRY to set , as both idle and governed speeds can only be re-adjusted/set during calibration(these affect throttle settings), and then APPS is calibrated as a complete assembly. Do reset only.

Tiger Rag sounds like could be injector issue/problem, fuel/timing box(remove to rule out as problem afterwards), or fuel injection pump issue. You said it was fine when trans was done, and showed up after inj were installed. Do you have fuel in your engine oil at all? Check for codes again, and do as Don M suggested to fix problem, try driving for a few more days(week) or so, to see if it goes away, and if no codes show up, and if you don't have fuel in oil. Then you may have to check crossover tubes/injectors more closely.

Tiger Rag

Torque, what would we look for to tell if there is fuel in the oil? I understand how the fuel would get there given the relation in space in the head, but just curious as to indentifying the fuel in oil.

APPS has been reset today with no improvement.

Talked to injector supplier. They were very helpful to have talked with us on a Sunday and said they've never had any issues like this, but would send a new set given our tests.

May try stock ECM to test if that could be the culprit.

Thanks again, Matt