Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

s300 and SManager software questions & answers
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eg-owns you
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Joined: Mon May 06, 2019 7:16 am

Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

Post by eg-owns you » Mon May 06, 2019 7:40 am

Good morning,

I have a fully built LS/Vtec with an S300 that was tuned many years ago. The car has been sitting in the back of a garage for about 7 years undriven. I finally got around to moving the car out of my parent's house and into my garage. I had issues from the start with it randomly throwing a cell rapidly. I finally had some time to data log a drive around the neighborhood and figured out I was throwing Error 8 TDC. I replaced the dizzy and lined up the middle timing mark with the mark on the timing cover.


This is where it gets weird. I am randomly having what I think is fuel cut and if I don't back off the throttle it will continue to give me no throttle response. I data logged a drive yesterday and at the 20s-24s on the graph, my duty % was 0%. This happens at any percent of throttle it doesn't matter how much/little throttle I give.

Any help would be awesome. I am not too sure how to read anything inside of the S300 data log.
Attachments
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20s-24s
data.PNG (109.22 KiB) Viewed 2086 times
orginal king tune.skl
Tune pulled from the ECU a couple weeks ago
(41.42 KiB) Downloaded 52 times
hiiiiiic.s3d
50 second data log 20s-24s duty 0%
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Spunkster
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Re: Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

Post by Spunkster » Mon May 06, 2019 9:57 am

It looks like you may have an issue with your TPS sensor as you can see it dropping and then coming back. I would recommend trying a different TPS sensor.

eg-owns you
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Re: Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

Post by eg-owns you » Mon May 06, 2019 10:42 am

I was kind of thinking TPS too but then why throughout the 20s-24s did I have 0% duty even when TPS was detected? I have another TPS laying around somewhere I will need to look for it.

crluver123
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Re: Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

Post by crluver123 » Mon May 06, 2019 8:37 pm

Spunkster wrote:
Mon May 06, 2019 9:57 am
It looks like you may have an issue with your TPS sensor as you can see it dropping and then coming back. I would recommend trying a different TPS sensor.
I looked over the datalogs when he posted this on honda-tech, and I suggested he post here.
What I found was that tps seems to be working normal, but every time the injectors cut, his rev limiter is active, with no relation to rpm or tps at all. No codes, and it happens at various rpms well below the set rev limit.
Please advise, as I'm stumped by this one. Possible faulty hondata unit?

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Re: Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

Post by Spunkster » Tue May 07, 2019 10:08 am

It may be a grounding problem as it appears to start as soon as the vtec solenoid is engaged. Check the thermostat housing ground and the ground on the stud of the valve cover. If it is not on a stud it is not doing anything.

eg-owns you
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Re: Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

Post by eg-owns you » Tue May 07, 2019 10:31 am

Alright, for the most part, the car drives great and cracks vtec without issues. I drove it for about 40 minutes last weekend and only could get it to hiccup a handful of times.

My plan of attack as of now:

- Check grounds (this car drove like a champ before it was parked for many years. I know the grounds are in the right spot. I will check for corrosion on the wires and clean them off if need be.

- I will be checking the ECU for any bulged caps or burnt diodes.

- Replace the TPS

I hopefully will have the time this Saturday / Sunday to screw around with it and update this post.

Thank you for the help!

eg-owns you
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Joined: Mon May 06, 2019 7:16 am

Re: Fuel cuts randomly on a fully built ls/vtec with dino tune from years ago.

Post by eg-owns you » Wed May 08, 2019 5:42 am

I had a chance to kick the tires last night for a bit!

-- I pulled the ECU out and checked over it for any blacken diodes or bulging caps. The ECU was in really good shape. I removed the S300 and resat it as well. I have added some pictures of the ECU maybe I missed anything?

-- I checked over my ground cables, the transmission ground and valve cover ground are in great shape they were brand new cables when I installed them many years ago. The thermostat housing ground was not so great the ground had a lot of corrosion and I mean A LOT..... I unbolted the ground and wire brushed the corrosion off tell everything was clean again and bolted it back.

-- I started up the car and let it warm up then took it for a drive. I was out for about 40 minutes and not once could I get it to fuel cut like it was. I even did some launches from a stop to WOT with 0 hesitation or hiccups. I don't know if the thermostat ground or me reseating the S300 in the ECU did the trick but right now the car is driving like a damn champ.

-- I will update this with any more data logs if I end up having any more issues.

Thanks for all the suggestions! I hope this wasn't a fluke! I will be taking it out and about this weekend so we shall see. I can not wait to get back out on the track!
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