Boost Dropping to Zero on Quad

[MH98.5]

Hello everyone!

 

I have read several articles posted around but cannot seem to find anyone that truly found an answer to my problem. I was recently driving my 98.5 that has a quad adrenaline and it started jerking. After a minute or so I noticed on my Bluetooth monitor that it would cut boost back to zero. As in, I would be going up a hill or something making 5lbs and then it would drop to zero and jerk. (Makes sense because I assume the quad cuts fuel when it sees the boost drop). At first I assumed the MAP finally bit the dust so I replaced it. It didn’t seem to help any. So I continued doing some testing and found the following: 

1. if I set the quad to level zero, the jerking is gone but it still shows boost cutting out on the monitor. 
 

2. if I set it to max power level and get the boost up it doesn’t appear to cut out. I was able to pull a steep hill for about 30-45 seconds holding 30 ish lbs. Maybe a fluke?

 

anyways, I would appreciate it if anyone has tracked down answers to this problem. 
 

thanks 

[Mopar1973Man]

Unhook the Quadzilla and watch the MAP sensor with a live data tool and see if it drops. If not then the Quadzilla has a problem with the boost fooler or boost circuit. If it continues after removing the Quadzilla then you have ECM to MAP sensor issue.

[MH98.5]

I don’t have a live tool I’ll have to buy one. Do you recommend anything specific? 

[Mopar1973Man]

OBDLink or similar. I've got only my Innova ODBII tool right now and it does live data well. 

 

https://www.amazon.com/OBDLink-Bluetooth-Professional-Grade-Diagnostic-Performance/dp/B07JFRFJG6/

 

[MH98.5]

Thanks Mike. Should be here Wednesday I’ll report back with my findings 

[wil440]

I have a 98.5 QCSB 4x4 and stock trans as far as I know, quad fitted a year ago, never really had the time to figure out my own tunes so I just run a towing and DD from here and wary of the trans was running the quad on level 3 and no more, bucked like a bronco BUT I thought it was lock up slipping so being VERY steady on the go pedal

I got that ##ssed with driving like your granny I thought wind it up and if the trans explodes I'll deal with it

Both tunes are now at the max level, truck pulls like the Flying Scotsman (and if you don't know what that is check it out) no bucking no cutting out,  I have no idea why as not got the time to work out why, Mike or Nick will know

going to be timing

 

[MH98.5]

Update. Unhooked the quad splice on the map and hooked it directly to the sensor. Went for a 15 minute drive and it never cut to zero. I’m thinking either something is wrong with the quad adapter harness or the quad itself. Was thinking about hooking up the adapter but disconnecting it from the quad harness to see if it’s in the adapter. Think this is worth a shot?

[Mopar1973Man]

Anything is possible but right now you proved the Quadzilla has internal issues with the boost fooler side. But yes double check the electric the best you can.

[MH98.5]

Just wanted to update this. FINALLY got it fixed. After a new map adapter, new ecm adapter, new OEM Cummins MAP, new Quad wiring harness, Quadzilla sent me a new module to try, none of which worked. Almost gave up and then I started messing with grounds. Well, embarrassing enough, it was a bad passenger side ground. Just goes to show how finicky they can be. Still can’t wrap my head around why it only did it with only the Quad hooked up and not all the time. Must’ve been because the Quad had a good ground and the sensor did not? Also, I can’t thank Quadzilla Kelton enough for going out of his way to help me every way he could. 

[Mopar1973Man]

Sounds like you need to do a W-T ground mod.

[IBMobile]

1 hour ago, Mopar1973Man said:

Sounds like you need to do a W-T ground mod.

And a PCM ground splice repair.

 

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/electrical/pcm-ground-splice-repair-r675/