Engine/Transmission (1998.5 - 2002) New 275RVs and new VP44...still a dog??

[steved]

Granted my truck has almost 100 more HP, but this 99 of my folks is still doggish. Replacing the VP44 and the injectors helped some (mainly at high RPMs), but it still seems lacking. It doesn't smoke under WOT... not even a little, like its not getting enough fuel.



What sensors control the fuel delivery??? A 24-valve is not my strong point, sorta remember an IAT and maybe a mass air flow or manifold absolute pressure??? None of this has been touched in 270k...



The fuel filter and air filter have around 6k miles on them, and this condition predates both of them... lift pump is good, and pushing at least 7psi (we have a light) at WOT.



The turbo sounds healthy, just acts like its not getting enough fuel. The VP44 and injectors made a huge difference in the idle (not smoking now) and high RPM driving, but anything around 1500 RPM is pathetic (unloaded, it will lose ground in 5th pulling any moderate grade... it should be able to gain easily)



What am I missing??? What should I be looking for??

 

[rjrkihap]

Hey Steved



Just a thought... you own and drive a 04. 5 which, at stock level, has quite a bit more power than the 99 (even with the new sticks). Could it be that your not use to driving a 99. I've upped the power a bit on my 99 and it was noticeable to me, however no where near the "seat of the pants" feeling I get when driving my friends stock 05.



Just a thought



Good Luck



Ron

 

[Regcabguy]

Throw a used EZ or other simple fueling box and an elbow on there. My '99 was a dog with just Mach 1. 6's . Combine an EZ to the equation and it was darn quick.

 

[steved]

I understand there is going to be a significant difference between his truck and mine, but I'm not even sure it runs as strong as it did when it was new.



I restate, it acts like its being restricted on fuel.

 

[EricBu12]

An Edge EZ is noticable. . I did a VP44 replace and had the Edge off for a bit. . Installed the Edge and big difference. Especially on the lower end.

 

[JR2]

Have you checked for boost leaks? Does the truck have gauges? How are the boost nuimbers? Have the valves ever been adjusted? Do you have access to a scanner to check for codes?



I would bet if you tighten up all the clamps on the hoses from the turbo to intake horn you will see a big improvment.



As far as the map sensor goes, it should throw a code if bad and if it is bad it will usually put the truck in limp mode. It would barley get out of its own way if that was happening.



The iat sensor is used to adjust the timing. It does not make a that big of a difference. You can pull it out an clean it and test it. There is a chart of temp vs resistance somewhere on here.

 

[PC12Driver]

The sensor with the biggest influence on fueling is probably the MAP (manifold pressure). If the ECM doesn't see boost, it won't add fuel. And MAPs can get stuck and not register higher boost values, but still stay within normal voltages, thus not setting a code.



Does the truck have a box of some sort?

 

[steved]

Truck is stock... except for the newly added 275s. Valves have been ran within the last 25k miles. Turbo acts like its spooling fine... unfortunately, no gauges on his truck... but nothing sounds like a boost leak. No codes, never has thrown one. The only other thing that's quirky is that his cruise control doesn't work... no codes, no blown fuses, just doesn't turn on.



I'm going to price both the IAT and the MAP sensors, and probably remap the APPS voltage (suggested elsewhere) at the same time. I'm not aware of any other sensors.



I will also check all the hoses (they are stock and have never been looked at), although wouldn't it smoke due to lack of boost and over fueling (or a catch22, no boost equals no smoke?)? He smacked a deer a while ago, I looked the intercooler over this past weekend when we changed the bumper (the deer never got that far) to make sure it wasn't cracked... nothing jumped out at me at the time.

 

[VolsFan]

I dont think you will see much of an improvement with just rv275's alone; not without a box or a boostfooler to go with it so it will go past the factory defueling point.

 

[steved]

What I'm getting at is the fact it is not even as strong as it was new... not that I expected 40hp to make a major difference, but I expected it to at least run like it did originally.

 

[jkalchik]

Wait a sec..... no cruise control either? Is there any chance that the ECM is stuck in a limp-home mode? Yes, I know, it should be throwing codes, and the CEL should be lit.

 

[steved]

I have scanned for codes, nothing my Actron sees... but that's not a dodge scanner...

The cruise started acting up over a year ago... it would sometimes drop out, getting the initial speed set was an issue... it is totally dead right now, which was news to me when I had it the past week. I assumed it was the typical control module for the cruise that gets attacked by the battery.

 

[LLiddell]

My cruise control quit when I was working on the drivers side of the engine. Turns out I had disconnected the vacume line that runs under the battery tray to the cruise control on the left side of the battery tray. Hope this helps.

 

[steved]

My cruise control quit when I was working on the drivers side of the engine. Turns out I had disconnected the vacume line that runs under the battery tray to the cruise control on the left side of the battery tray. Hope this helps.

No, quit working and totally dead are two different things... I can't even get the "Cruise" light to illuminate on the dash... just like a truck without cruise.

 

[FLynes]

steved, I second LLiddell's post. On my '97 my cruise quit working... turns out that the battery had leaked, and the cruise vacuum line, which is located directly under the battery tray, had a hole in it from the battery acid. I had to cut the line and reattach it. Cleaned up the battery tray and never had another problem. You might try that.

 

[steved]

steved, I second LLiddell's post. On my '97 my cruise quit working... turns out that the battery had leaked, and the cruise vacuum line, which is located directly under the battery tray, had a hole in it from the battery acid. I had to cut the line and reattach it. Cleaned up the battery tray and never had another problem. You might try that.

If that was the case, the light on the dash would still illuminate (at least turn on; it might not work, but it would turn on)... its like the fuse was pulled for the cruise control on his.

 

[FLynes]

My cruise light didn't illuminate. I'm not sure if the 99's are different from the '97's but vacuum is what engages the cruise and, if that hose has a hole in it, then the cruise won't work, so you wouldn't get a light.

 

[steved]

I was under the impression the cruise was controlled by the vacuum actuator, but electronically turned on and off??

I had my hand under the battery, there seems to be no corrosion... but I could not verify that.

But that still doesn't answer the low power...

 

[HBarlow]

When my '01 with 275RV injectors had just under 100k on the odometer a mechanic who pulled the starter and replaced the contacts with the aftermarket kit that used to be advertised in the TDR magazine apparently bumped the MAP sensor by accident.

Suddenly my normally very healthy HO6 speed started running weak, could not make smoke, and would not make full boost.

The problem was the MAP sensor. Dodge repair manuals describe the tiny voltage output that should be present if you measure its output but I don't remember what the numbers were, it was five or more years ago.

I'd replace the MAP sensor. It's a safe bet.

 

[SWiller]

i would also check out the map sensor as well. but with the extra fuel from the bigger injector's the boost will rise as well, so it might be defueling? I would hook up a boost gauge and post up the results. you might just need a boost fooler or step up to an ez or comp. hope this helps.