Started the install of the MP-8, RP gauge, and new boost and fuel pressure gauges. Having some issues. very rough idle and rich smoke, threw 3 codes, p2121 unknown code, a p 0652? low sensor voltage, and a WIF code. Tried putting the plugs in every possible scenario, no luck. Now even when I have the stock plugs only plugged in I'm stil having a rough idle. When the RP gauge was plugged in it was reading 5500 psi RP. I'm done screwing with it for tonight, frustration has overtaken patience, left the batteries unhooked for the night.

What order should the plugs go? (stock, MP-8, Quad RP gauge)?
Does anyone know how to alleviate this issue, or have experienced it?
Will di-electric grease maybe solve some issues?
Is there anything wrong with grounding the MP-8 on the battery?

Also, being i have the AD100 the banjo fittings no longer exist on the CP3 or pump. I have a Isspro Fuel pressure gauge, how are ya'll tying the fuel hose to the isolator? I need some serious help, my truck will be down tomorrow until i can figure this out, I really need some help, whether it be simple or not. I know this has been covered before, but i don't have time to search for what I need. I am running the 4.4 beta, sw 3 currently but normally sw5. PLEASE HELP!!!!!!


Rick

 

For the fuel gauge, i used a T fitting that is made the same way as the fittings that come with all the fuel pump hoses, and cut off a little of the extra blue hose, and ran it from the T up to my isolator. BTW it may take a while to get that thing to work right and get all the air out of it.

 

Thats what I was expecting. Did you put antifreeze in your isolator like the instructions said? I went ahead and did that, I assume its to keep it from freezing in the cold? Thanks for the response sir!

 

Because you have the WIF light on you plugged one of your plugs in backwards. Been there done that. I would think it would go RP gauge then the MP-8. Make sure they are both plugged in the correct way. It is very easy to plug one in backwards.


Edited: Plugged in backwards on the Railpressure sensor just to clarify.

 

We've tried every combo possible, and it ran the same no matter what. I did clear the codes a few times. I figured something was wrong, but when we change it it doesn't change anything. Everything is brand new, nothing used before. I'm bummed. Thanks Spooler.

 

Any other insight is appreciated. Bout to hit the sack, Hoping things will be better tomorrow.

If anyone wants to add to the plug fiasco please do, I need an understanding of where I should go from here.

 

Did they work one at a time. Or did you try them each by themselves first?

 

I put the RP gauge first, then the MP-8. If you do it the other way, you will get a false RP reading because the MP-8 changes the signal. I would start out from the beginning. What P/N MP-8 do you have, is it correct for the 03-04? I know when I got mine it had a box-o-harnesses and I had to change wires in the connector but I think they are different now. Like others have said, its extremely easy to plug in the connectors backwards.

 

my mp8 when i fgot it had one loose wire on the **** and it threw some codes and had rough idle might want to look at that close

 

Thanks ya'll, gonna go scope some stuff out. We had the two plugged in together, but the truck wouldn't crank, so we cleared the codes and flipped the switches. Still had rough idle, but the truck started and ran. Then we cleared codes again and tried one by one, and it still idles rough, but no codes. So I will be checking for loose wires and get some dielectric grease for all the plugs. I will also get the part #, I'm sure it said 03-04 on the box, but maybe the box is wrong. the RP gauge seemed to be working fine when it was plugged in, as i said it was showing a reading of about 5500psi at idle. I really appreciate it ya'll, keep the ideas coming!

Rick

 

Well, I read the instuctions again and got dielectric grease, coated all the plugs, and one by one placed them. Hooked the batteries back up and all is good! I'm so relieved, so i went out and tested everything. The MP-8 definitely gives a kick on the mid and high range, but only adds more smoke on the lower side. It definitley makes things more responsive!

My RP readings were as follows:

Idle- 5500psi
normal cruising @65-70mph- 16,000psi
moderate throttle- 20,000psi
wot- 24,500-26k psi

This is with the MP-8 set about 50% and the 4.4 on sw5. the spoolup is awesome and I'm topping out at 42psi on the HTT. Don't know egts because the pyro is still broke, and I'm gonna work on the hose to isolator in a little while. Thanks for the support ya'll!

 

Called DieselManor, got a new gauge coming to me, no questions asked. Couldn't be happier with the results.

 

Just curious what the rp would reach without the MP8?

Chasing some rp issues myself...

 

It was reaching 23k psi with the MP-8 on 0, 26k with it at 100. How have you been doing?

 

Max rail pressure around 18-19k with smarty on stock rail pressure setting. Now that I have it on the mod setting, I've seen 21k once...

I capped the rail thinking it may be leaking. No change.

Stock injectors, GDP lift pump setup at 25 psi, tried two modded FCA's same results.

Also, when I let off the throttle on the highway, rail pressure will drift up to around 15k and stay there until I get below 10 mph or get back in the throttle. If I get back into it, it will quickly drop to 5k and then back up (feels like a deadspot).