My car absolutely hates Direct Scan

[litdog83z]

Whenever I hook up direct scan, my car will drive around fine most of the time, but sometimes it bucks and throws a code (something to do with the ignition system). Then it'll run crappy for a while then buck and run fine again

Unplug direct scan cable from the ECM and it's fine again.

Then tonight I took iout the ECM and plugged the cable in again and did some datalogging.. At about 55 mph I punched it and boost flew up, car started pulling nice, then bucked and Direct scan showed a code 51-faulty EPROM.

It also dropped out most of the readings on the display for a second (and in the recording) and told me I was making 3000 ft/lbs of torque (I wish )

All of the readings look fine at idle and cruise, except for an occasional random BLM cell jumping 10 points

I unplugged the cable from the ECM, and it pulled nice and hard with no sounds of detonation or anything all the way up to 85mph... Only problem was blowing out another turbo to header gasket ... Boost was set at 12psi (no more wastegate solenoid - Dutt neck IC and stock wastegate arm...need to adjust the wastegate arm to up the boost) I also have a turbotweak chip.

So any idea how to fix this? I put a ratchet tie thing in there to space the plug out some so it doesnt go on too far, and I also put 3-4 layers of aluminum foil around all of the cable by the ECM.

 

[PaCemkr86]

http://www.chuengineering.com/


DirectScan EMI Shield

Some vehicles by nature produce more EMI noise than other vehicles. This "noise" emminates primarily from the ignition system - i.e.: spark plug wires, ignition coils, etc. This noise has been known to transfer onto the DirectScan ECM ribbon cable and cause erratic behavior.
Known behavior / symptoms include:
Normal operation while cruising but suttering at WOT.
Strange, intermittent "hickups" or stuttering during vehicle operation (idle, cruise, and / or WOT).
Only occurs when DirectScan is attached to the ECM. The laptop can either be connected or not to show these symptoms. The symptoms have also been known to occur with just the ribbon cable attached.
To remedy the issue, an EMI shield can be placed over the ribbon cable to prevent this noise from coupling to the ECM. If you believe that you need the shield, please contact Conley's Performance Plus at (281) 540-FAST to request it. As with any service call, please have your unit serial number ready.

 

[litdog83z]

so the aluminum foil isnt going to be good enough for me... I remember reading that somewhere though... I wish this is why my car is killing turbo to header gaskets :frown:

 

[PaCemkr86]

what ive found on blowing various header gaskets on my TR was the sealing surfaces have to be flat/true.

 

[ijames]

Pull the ecm out of the car so you can take a very close look at the ribbon cable card edge connector and how it sits on the ecm card edge. Sometimes one or both sides of the card edge are too wide or too narrow and the connector can shift sideways and randomly short out traces. Same result as if the connector went on too far, just a different way to get there. See if you can push the connector side to side while keeping it seated. You may need to file one side of the card edge to let the connector move over, or build one side up with epoxy to keep it from moving.

 

[litdog83z]

I just looked at that and it doesnt seem to slide much... maybe a tiny tiny bit. The ratchet tie strap thing I was using had moved a little bit so the big end where the little end threads through was on the edge of the connector, so maybe it was a little crooked... and still it's only about 1/8 inch wide... maybe I need a thicker spacer?

Anyone have any tips/dimensions on making a better spacer for the cable?

 

[WSLN 6]

I used some wider tie straps, about 1/4" wide, stacked 5 high and wrapped with electrical tape. Made a nice solid stopper for the directscan cable. Make sure that tinfoil is also taped to the ecm case, and that it isn't touching any part of the connections on either end of the cable.

 

[litdog83z]

So maybe my cable is still pushed in too far... i'll investigate this tomorrow and find something nice to use as a thicker spacer

 

[ijames]

I guess I don't understand where your spacer is? To keep the connector from going on the board too far, Ken Chu suggested laying a toothpick inside the connector. I've done that, and also cut the head off a small plastic cable tie and pushed that down to the bottom of the connector.

 

[BoostKillsStres]

On the edge connector spacer topic: I decided I didn't want to stuff anything in the ribbon connector as once its in there its most likely not coming back out. I took an xacto knife and some dense fiber type material and rectangles and cut a slot in it in the shape of the edge connector. I cut several of these so I could vary the stack height. I then put several of them on and looked very closely at the pin rubbing taking place on the edge connector when the ribbon cable was attached then taken off and I adjusted the stack heigh until the connection looked optimal.
HTH

 

[litdog83z]

I guess I don't understand where your spacer is? To keep the connector from going on the board too far, Ken Chu suggested laying a toothpick inside the connector. I've done that, and also cut the head off a small plastic cable tie and pushed that down to the bottom of the connector.

I put the zip tie around the ECM board where the direct scan cable pushes on to. I didnt think about putting the toothpick IN the cable's end... maybe i'll try that. It seems like a lot better idea. Just one toothpick is enough?

 

[litdog83z]

I put a spacer inside of the cable connection and plugged it in, same stupid crap It's really starting to make me mad cause I want to turn the boost back up already...

 

[BoostKillsStres]

yep, its a real PIA. On my car it took everything to stop doing the skip/drop/code hickup. Super clean edge connector, correctly spaced and shielded ribbon cable with the shielding forced up against the ecm case for complete grounding.
HTH

 

[litdog83z]

OK, i put in another length of zip tie inside the connector to space it out where it barely goes on. We'll see if that'll work.. I might also shorten the cable.. And i'll tape the foil and cable right down on the ECM.

Is the area around the ECM the main spot it needs to be foiled? or all the way up to the DS hardware box?

 

[litdog83z]

ok so it's just barely making connection now, but i still get readings.

I also taped the mostly aluminum foiled cable to the ecm and ran a ground wire to the case for extra insurance.

This time I thought I had it. from a 40mph roll i could floor it and it accelerated to 76mph and then jerked again, throwing 10 trouble codes

This is only with direct scan hooked up too... It didnt used to give me this much trouble at WOT with the stock chip... It would just be slow and run crappy, but no popping and bucking. I'm gonna hit radio shack and try and find some electric shielding tomorrow and put it on the full length of the cable, but other than that it's getting pretty ridiculous

 

[TurboBob]

shortening the cable will really help. A short cable with shielding will probably fix it for you.

Are you running a power cord to the laptop, or just on batteries.

Bob

 

[litdog83z]

shortening the cable will really help. A short cable with shielding will probably fix it for you.

Are you running a power cord to the laptop, or just on batteries.

Bob

batteries

 

[wants a tr]

hey,

i live 2 miles from edmond...drop me a line and i can probaly help you out with this...

that is if your car is here...if its in MO...good luck =]

joshgn@cox.net

 

[VIN7]

I went through all of this too. I got the sheilding from Kent, still had the problem. Go back and reclean the ecm "fingers". I used a scotchbrite pad and acetone. This is what worked for me, I was at the end of the ideas since the connector was not removed or disturbed and the bucking just started happening one day. Cleaned the ecm card and all's good.

mike