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Discussion Starter #1
I have been on this site and asked a few questions but mostly read to gain the knowledge that is here free for the taking but here is my problem


I have an o4 w900 with a 01 6nz motor in it I have tried everything under the sun to get it to run right and have had it to shop after shop and even posted the problems on here but still not running right here is my question i see that there are some really smart guys on here that answer alot of questions for people and i was wondering if any of them happen to run a shop that i could take this thing to and have it looked at.... if i take it to cat they wont work on it do to the ecm turbo and ect that are on it

so if any one could steer me too the experts please and thank u


BIGTIME
 

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Where are you located? That will help determine who might be in closer proximity to you.
 

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Try YNOT. He has been doing
cat,s forever. (Or maybe not that long!) Or maybe 379Longhood.Like bpogue said, it depends on where you are or where you can go. Good luck.
 

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Discussion Starter #4
I live by rochester mn but I get all over and realy distance is no problem if were ever it is thinks that they can fix it just say the word and me and the check book will be on the way

thanks for the replies
 

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My experience is mostly with mechanical engines. but there are lots of guys here who could prolly get it right for you, Mr Haney knows how to get HP out of electronic cats , Tony , Sled, Robsredford,SmokenCat, bunch of others my mind can think of right now Sorry to the guys I missed listing. Location is the big one.:toytruck
 

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631 Posts
I have been on this site and asked a few questions but mostly read to gain the knowledge that is here free for the taking but here is my problem


I have an o4 w900 with a 01 6nz motor in it I have tried everything under the sun to get it to run right and have had it to shop after shop and even posted the problems on here but still not running right here is my question i see that there are some really smart guys on here that answer alot of questions for people and i was wondering if any of them happen to run a shop that i could take this thing to and have it looked at.... if i take it to cat they wont work on it do to the ecm turbo and ect that are on it

so if any one could steer me too the experts please and thank u


BIGTIME
Is this a BXS serial number engine with a 6NZ ECM on it or is it a complete 6NZ engine installed in the truck to replace the BXS?
 

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Discussion Starter #8
Thanks MR. Haney for the reply

No it is a complete 6nz the truck had a mbn motor in it i bought this 6nz and installed it

this motor is running a c-16 flash file and a stage 1 turbo and the thing just is not right i have switched it all back to stock ecm and turbo and still has a miss and flutters when pulling and the fuel milage is real bad and when i first did the ecm and turbo it was great so if you have any ideas or a place i can bring it i am all ears thank u very much
 

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Have you run a valve set? check you oil filler at idle cold engine see if you get any pronounced blow by puff, put a clear hose in the fuel line to check for bubbles.
 

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Ever have a cut-out test run on the injectors? 5 outta 6 took a dump (MBN engine) and Tony replaced them for me. Mileage back and so is the power. :)


How is the fuel pressure at idle and WOT? Severe pressure drop under load?

A weak transfer pump and bad fuel bypass valve were 2 contributing factors on my tractor.
 

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Discussion Starter #11
I have had the overhead ran several times no change, we have done and injector cut out test show all good the fuel pressure is running a 96 at idle and around 110 while going down the road and about 95 to a 100 in full pull we have check for air in the fuel and it looks like that is fine also

somtimes when i idle overnight the truck is smooth and then there is no blow by but when u idle it and it is running ruff it will have some steam coming out of the blow by tube

when u try and idle through a parking in lot and just barley have your foot on the pedal it will flutter and pop out the stacks and when you are in a full pull it shutters and will send vibration up the stick

when i first did the ecm and turbo this thing would put quite a bit of black smoke out between shifts and now there is not much at all

I had the ecm done at a shop out in PA and it ran great when it was done now not so good
 

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Did you stand next to the tech when the cut out test was run? When were the last tests done?


The numbers weren't bad the first time I had it done, but my ear could hear 2 weak holes. 2 and 3 at the time. The guy doing the test didn't pick up on it. Had him run both tests twice. I knew there was a problem 1.5yrs before it was so bad that there was no 2nd guessing it by anyone. I live in it, so I knew. But anyone else, it was subtle enough they didn't pick up on it. The loss in mileage on the old set would've paid for those new injector several times by now.
 

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Discussion Starter #13
Yeah i have stood right there when they have done it and alls they say is that they are with in spec

one other thing that might help out is the engine was just overhauled 15000 miles ago and the injectors were all put in new along with cam and head front cover gears were gone through also

I am thinking that it is electrical myself but by far am not and expert that is why i am on here asking u guys what to do or were to go

thanks

BIGTIME
 

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I'd check the wiring under the valve covers. Easy enough to get one pinched.

Cat has had some issues with reman injectors.
 

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Discussion Starter #15
new wire harness from ecm to engine and also new injector and jake harness under the coveres

what i was wondering is if any one has seen any trouble with the harness that comes from the fire wall to the ecm because if i am thinking correct that would have say your throttle position sensor wire and others that could cause a problem maybe what do you think
 

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A new set of injectors, doesn't mean that one can't be acting up. CAT hasn't had the best quaility control on injectors the last few years. This is a hard problem to fix without hearing and seeing what's going on. First thing I'd check is injectors, even if I had to pull two at a time and put new ones in those cylinders. If that didn't cure it put the first two you removed into the next two cylinders. If you go through the whole engine without fixing it........the next thing is a possible head gasket. I'd also pull the valve train and inspect the camshaft lobes for flaking............you've eliminated the electronics with the ECM and wiring harness changes..........now you need to look at the mechanical possibilities
 

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Discussion Starter #18
the injectors that are in it are the ones that came in the overhaul kit also installed a new camshaft when we did the overhaul

I was wondering if the wire harness from the fire wall to the ecm could have anything to do with it not sure just thought that was probaly were the tps wires ran out to the ecm
 

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Have you checked the ECM for fault codes? The TPS wouldn't cause a miss or flutter.........it would be a loss off power. If it totally loses signal it would be the same as taking your foot of the throttle momentarily. You need to have someone in the truck with you with a laptop hooked up watching the motor and how the sensors are responding to work. You can have a mechanical problem with an injector and not have any fault codes. If there are no fault codes, I'd be leaning towards a mechanical problem. If you can't find anything while driving with CAT ET plugged in...........then I'd say you have a mechanical problem. If you can isolate it to which cylinder is causing the rough running then you have a much better chance of finding it. You can also use CAT ET to turn injectors off one at a time and listen to see if one cylinder is weak compared to the others. You may have to put the truck on a dyno to see if you can duplicate it then isolate which cylinder it is.
 

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The poping at low rpm with barley any throttle sounds familiar. 2 times the tech ran the overhead and set the valves to what , he , thought was a good feel. The third time set them to a " no drag,, free feel " the problem was fixed. The low speed poop poop sound and the weird da da da in a hard pull sound was gone too, everything dead smooth, that tech was me.. and i have done hundreds of overheads, not that many on Cats. I would go back threw the overhead one more time and make dead certain that this is not whats happening.
 
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