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JoshT800 · 10-10-2020, **(Subject: Won't Rev past 1500rpm )**

My Kenworth T800 developed a problem where it won't rev pass 1500rpm, no matter the speed. It has an ISX CM871. The speedo is working, don't know if there is another sensor i should check or change. The truck was parked for a little over a week, before that everything was good.
I scanned it and got 2 errors non-relating to my problem which was to do with the particulate filter, which was unplugged since before.

Any help or ideas would be very appreciative.

Signature620 · 10-10-2020, **(Subject: Won't Rev past 1500rpm )**

Most KWs have 2 speed sensors on the back of the gearbox. 1 for the cab and 1 for the engine. If so, swap the plugs around and go for a drive. If the speed doesn't work but the engine revs above 1500 then you've located your issue.

Rawze · 10-10-2020, **(Subject: Won't Rev past 1500rpm )**

ecm loose some settings?

if the DPF is unplugged,.. got any check engine lights?

if not, and it is deleted... should also pull a copy of the program out of the ecm and e-mail it to me for review. could be a sensor or system or derate activeand errors for it suppressed from showing up in the dash of the truck ,,.. I.E. a programming issue.

JoshT800 · 10-11-2020, **(Subject: Won't Rev past 1500rpm )**

Thanks, but the truck has only 1 speed sensor at the back, I unplugged it and the speedo stopped work. My Brother has an International with the same engine, when i Unplug the speed sensor it won't rev pass 1500 and the speedo won't work too, plug it back in and it's back to normal.

To answer Rawze: I unplugged the diesel particulate filter and it through the check engine light. The truck worked fine for weeks after that. Parked it for about a week and then this issue. Before I bought the truck, I told the company to step up the hp to 500 and make sure the DPF is deleted. I paid them $1200 to do that, but i don't think they did.

I also noticed the turbocharger speed is about 18000rpm at idle, on 1500rpm it's about 52000rpm. Is this normal?

Rawze · 10-11-2020, **(Subject: Won't Rev past 1500rpm )**

(10-11-2020 )JoshT800 Wrote: Thanks, but the truck has only 1 speed sensor at the back, I unplugged it and the speedo stopped work. My Brother has an International with the same engine, when i Unplug the speed sensor it won't rev pass 1500 and the speedo won't work too, plug it back in and it's back to normal.

To answer Rawze: I unplugged the diesel particulate filter and it through the check engine light. The truck worked fine for weeks after that. Parked it for about a week and then this issue. Before I bought the truck, I told the company to step up the hp to 500 and make sure the DPF is deleted. I paid them $1200 to do that, but i don't think they did.

I also noticed the turbocharger speed is about 18000rpm at idle, on 1500rpm it's about 52000rpm. Is this normal?

you should assume your delete programming is bad.

Did they also hollow out the DOC and DPF elements 100% open? -- install any block plates? etc.etc?

Do you have laptop with insite and an adapter?

your posts point strongly towards you not knowing much about this subject in general and that leads to someone being taken advantage of and consequently ripped off. 90% odds are against you that your programming is any good. Here is some education for you...
http://rawze.com/forums/showthread.php?t...5#pid13255

We see every week on here all the bad deletes these shops do and people who have gotten taken for all they are worth.

For all you know, the thing may have gone into an rpm derate. You can't just unplug stuff without the engine eventually limiting rpm to penalize you over it, ... and eventually shutting down.

Your on the fast track towards a destroyed engine.. that is the road you on it sounds like to me.

Nilao · 10-11-2020, **(Subject: Won't Rev past 1500rpm )**

Yup, $1200 is too cheap. It's a good days labor to remove everything and fix it to work with the programming then putting it all back. Then most reputable people charge 1200 or so for the tune alone.

Waterloo · 10-11-2020, **(Subject: Won't Rev past 1500rpm )**

You have a bad delete, if they even did one... I bet the cans are still intact and they did nothing other than lighten your wallet by $1200. You need an Inline reader and Insite software. eBay is your friend, search Cummins Inline 6 reader, they are out of China or Hong Kong, around $200 to $300 bucks, has everything you need to see what you have in the ECM. You need to get one if you do not have one already, and get the current tune to Rawze to evaluate. And if I were you, drop the cans and see what they did, if anything. Time to take ownership of that truck.

JoshT800 · 10-11-2020, **(Subject: Won't Rev past 1500rpm )**

I have the Texa Software from Diesel Laptop that does all my scanning etc. When i scan the truck, it only shows the error of the DPF being unplugged. I would put my ECM on my brother's truck and see the results.

Rawze · 10-11-2020, **(Subject: Won't Rev past 1500rpm )**

(10-11-2020 )JoshT800 Wrote: I have the Texa Software from Diesel Laptop that does all my scanning etc. When i scan the truck, it only shows the error of the DPF being unplugged. I would put my ECM on my brother's truck and see the results.

get yourself an inline-6 adapter, insite and CT.. get the stuff to properly work on that truck.