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Discussion Starter #1
Having an issue with randomly breaking up during and after my tune.

89 si built a6
obd1 td41u rich porter new dizzy with obd0-obd1 jumper
p28/s300(hondata)

turn the car on, no cel, after about 2 clean wot pulls it breaks up around 5k all the time after. side not during those rare clean wot pulls it does not rev past 7k. once it breaks up, shortly after cel pops up for crank angle sensor. e
turn the car off for a few mins and and when you start it back up it will stay off for a short while.

you can turn the car off for a short while and start it back up, cel will be gone and but will repeat what it does above almost to the t.

anyway long story short, not sure why or whats going on.

i have not tried not going high rpm and just driving it for a while and see if the check engine light comes on. ill try that later today.

my tuner told me it might be the dizzy so..

swapped out the rich porters ignitor and coil for a known working one, did the same thing, a few wot gears and then broke up and then shortly after cel pops up.

swapped in a new duralast dizzy, same thing a few wot gears and then breaks up and cel pops up.

maybe its the ecu, im going to try swapping in another p28/s300 and load my tune on it and try that.

any idea here guys ? things i know, tune is spot on, it will manage a few super clean pulls before breaking up and throwing the cel shortly after. so i can eliminate the jumpers causing this. could possibly be two bad dizzys, as ive heard dizzy issues are common when using non-oem dizzys. but the likely hood of two ? there is a crank angle sensor in the dizzy and their is also a crank angle sensor behind the crank ? but it never once popped up prior to the changes during the tune (dizzy + ecu plus jumpers.)

kind of lost, this is my first honda build. any info would be greatly appreciated.

stratton.
 

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90 crx si/96 accord
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I vote for wiring, the engine harness is 27 years old, and the ecu needs to see a CLEAN 5V square wave signal from the corresponding tdc/cps sensors. Add into the mix of a jumper harness....ya,
 

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Discussion Starter #3
If I dont rev past 5k or so and make it break up so to speak it wont throw the code and run perfectly.

That would lead me to belive its not the wiring or the jumpers. it never threw any codes prior to the jumpers, obd1 dizzy and obd1 p28.

stratton.
 

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Premium Member
90 crx si/96 accord
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788 Posts
It could be the ecu, it could be the jumper harness, it could be a bad spark plug wire, maybe your gap is to tight or loose, or, maybe your unwilling to admit that using 27 year old wires, wires that are THE LIFELINE as to how the engine performs and operates, MIGHT be an issue.

Ya I get it, it ran fine before you did all that , my 26 year old wiring ran my car" fine" also, but wanna guess how much better and awesome it performed when I ran brand new wires and terminal straight from the ecu to the sensors?
 

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Discussion Starter #5
its not a bad spark plug wire because its the same wires i ran prior. prior to friday night i had ran the car to 7200 hundreds of times, for close to year.

it dynoed at 138whp on the stock obd0 untuned ecu. it is a built motor. and the car is in amazing shape ! but i do understand what your saying. car never gave me a single issue prior to the night of tunning/swapping alot of stuff around.

i have another p28/s300 to load my tune onto and try out. so that will tell me if its the ecu or not.

i also found some one with a obd1 dizzy that ive been told is oem to try out.

only other thing it could be is the jumpers, if thats the case i will order a new set from Rywire tomorrow.

i will get to the bottom of it.

btw the break up isnt so much a bog or a sputtering as it is a complete loss of hp, shift into a higher gear and have the rpm's below 5k or so it will run and drive fine.

only a few more things to try. figured id just ask if anyone had a similiar issue. if not it will help those who do in the future.

thanks for your opinion and help.

stratton.
 

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Prelude, Integra DB9
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This may be complete nonsense, but it sounds like it's going wrong at vtec cut-in revs ...

Can you get hold of the original ECU (PM6?) to see if the P28 is trying to tell the engine to do something it's not designed for?
 

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90 crx si/96 accord
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Personally, I would avoid the jumper harness, and do a hard wire obd1 conversion. I had 2jzdreamin (a forum member here) sell me the pins and various connectors and seals, and made my own harness from the ecu to the engine, after it was all said and done, I went on my first test drive and noticed it pulled harder, and more importantly, SMOOTHER. shit, before you spend the money on a different jumper, you should p.m. Him and see how much his harness is if your not up to doing the wiring yourself
 

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Discussion Starter #8
This may be complete nonsense, but it sounds like it's going wrong at vtec cut-in revs ...

Can you get hold of the original ECU (PM6?) to see if the P28 is trying to tell the engine to do something it's not designed for?
i could get ahold of pm6 down the read if nothing else works. if i remember correctly the tuner had to set it for vtec on but set it for like 9 grand. then we could rev the motor higher. oddly the motor will rev to 7200rpm a few times before it starts breaking/dying down.

Personally, I would avoid the jumper harness, and do a hard wire obd1 conversion. I had 2jzdreamin (a forum member here) sell me the pins and various connectors and seals, and made my own harness from the ecu to the engine, after it was all said and done, I went on my first test drive and noticed it pulled harder, and more importantly, SMOOTHER. shit, before you spend the money on a different jumper, you should p.m. Him and see how much his harness is if your not up to doing the wiring yourself
well the reason i did the jumper harnesses was for the simplicity factor, simple and easy and i would have to hack up a perfectly fine working obd0 harness that is surprisingly clean and intact.

updates for tonight.

-swapped my hondata onto another p28 and it still broke up but the cel did not come on. even after forcing the motor to break up/die down.

-swapped in another jumper harness but i could tell just by the idle it was bad and also when i free reved it it would break up like it did before while free reving even with out even driving the car and the cel would come on.

so with that being said, i think it is the jumpers, with a possibility that the ecu also has a issue. but im along with many other people towards it being the jumpers.

i will purchase two new jumpers, dizzy and ecu from rywire tomorrow and have them 2 day shipped to my house.

ill try them with the ecu that didnt throw the cel and if it works 100% ill swap in my p28 that threw the cel and see if it still does.

thanks everyone for your time.

hopefully one of these options fixs the problem.

ive tried two dizzys, two ecus, still the same issue, only logical option next in line is the jumpers.

ill be back in two days.

stratton.
 

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Discussion Starter #9


this picture doesnt clearly show how clean the wire harness is, but it shows the overall condition, everything is in its oem place, the wire harness in the bay and in the part that connects to the ecu are in great shape. cleary its possible that it is a bad wire, but im not about to go threw the entire harness to find a faulty wire, ill try the jumpers.

worse comes to worse ill purchase a brand new obd1 engine harness but hopefully thats not the route i need to go.

like i said the car ran hard, super smooth and super reliable for many years [rior to one night of jumpers, dizzy and ecu. so ive been threw 2 dizzys, 2 ecus, jumper is next in line !

stratton.
 

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Discussion Starter #11
it was a bad set of obd0 to obd1 jumpers, that were purchased from a ebay seller.

i installed a set of RyWire ones early today and she ran like a dream !

new it had to be one of those three. good info here for anyone who has similar issues in the future.

stratton.
 
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