Need help troubleshooting...

Finally getting around to working on the car again. Funny enough, watching Roadkill Garage has given me some motivation to get it going.

So today I removed the pull ups from the loom and did some significant cleaning up of the wiring (mostly rerouting/reorganizing) as it was a logistical mess. I still need to rewire my coils and injectors. Before I had all that bundled with everything and it passed around under the manifold, up between the mani and thermostat, then back to the coils and injectors. To simplify and make future diag easier these components will be separate. I'm either just going to branch off at the firewall and head straight to the injectors and coils, or I was considering maybe going under the manifold and popping up between the 2nd and 3rd runner.

I'm also working on separating the wb controller wiring from the main loom to facilitate ease of replacement if it goes bad or I upgrade to a different controller down the road.

This week I'm soldering jumpers with pull ups directly to the board. This is the way I wanted to do it from day 1 but I didn't want to risk voiding a warranty.

I guess this is the long way to fix my ground issues but figured why not just do all this to make life easier for the long run. Hope to have this thing fixed in the next couple weeks if my back will allow.

Well things are getting better. Here is what is different from before:

1. Removed 5v pull ups from loom and soldered to board
2. Cleaned up and checked all grounds (sensor and power) in the MS harness work
3. Moved power ground for coils from intake mani to the cylinder head where the kjet hard line bracket was
4. Removed crusty ground strap from back of cylinder head to cowl. Used thick gauge ground from cylinder head at kjet line bracket to the strut tower.
5. Corrected Spartan 2 grounds per manufacturer power ground to cylinder head (where old crusty strap was) and sensor ground to battery neg terminal.

Key on not running I've got 4.92v at vref. Cold start and cold idle it was holding steady as well at same 4.92v. I turned off my meter at that point as I wanted to let it warm up. After warm I checked vref again and it's slightly higher than 5v. Some fluctuating at idle but it actually drops down towards normal instead of the jump up to 6v from before. I'm getting some voltage from the negative battery terminal to the block that fluctuates with rpm.

Drive link has vids of the two above items if anyone is curious:
https://drive.google.com/folderview?id=1ab0P8letfjHofUqVCPQidJhoM2f8WUve

I ran out of time and didn't get a chance to get my laptop out to look for any abnormalities. I thought it odd the vref held initially but then fluctuated after some time. Tomorrow I'm going to cold start it again so I can keep a close eye on the vref and see how long it takes until it starts fluctuating again. See if maybe that correlates to something else.

So long story short some positive movement. The ground issue is odd.

I got a few minutes free this morning to spend with the car. Probed the vref, completed the cold start, and watched the meter. It fluctuates slightly from 4.91 to 5.05 or thereabouts. There is no point when it just jumps to that higher reading I saw yesterday...the range of fluctuation increases as the car warms up. I'm going to guess the voltage at ground might do the same thing but I'll need to wait until the car is cold again to test that theory.

Since it was easy to do and because of my improper grounding of the WB controller on the initial install I pulled the fuse and both ground points thinking maybe there was something there screwing with my grounds. No change.

Since it seems to be temperature related I gave the air and coolant temp sensor connectors good shaking then disconnected to see if any impact. No change.

As soon as the car is cold again I'll test the ground as it warms up. I'll run a log at the same time too (didn't have time to mess with the laptop this morning).

I've ruled out the coils, MAP, TPS, WB, and temp sensors. All my wiring is rock solid. The only thing I can think is perhaps the CAS is going on it already? I'll need to see if the log can give me any indication there. My google searches aren't coming up with a lot of good testing info on the CAS but I'm going to hit that harder this week.

Uhhh, I looked at your video and you want to set your meter to the 20V DC position. I don't know what the 9V BAT position does, but it might be screwing up all your measurements, especially if it's trying to load down the circuit until the voltage drops.

bobxyz said:

Uhhh, I looked at your video and you want to set your meter to the 20V DC position. I don't know what the 9V BAT position does, but it might be screwing up all your measurements, especially if it's trying to load down the circuit until the voltage drops.

Click to expand...

Oh wow...I have no explanation for why it was in this position yesterday morning as I've been using the 20v DC position all along this adventure. Verified I get the same readings with the 20v DC position, though.

I found a manual for your craftsman meter, and the 9v BAT setting only loads the signal with a 1.5K resistor (6mA), which won't affect your measurements. The 1.5v BAT setting adds a 15ohm load (100mA), which will drag down most Vref and sensor measurements.

The variation shown in your video, ~4.9v to 5.6v, is still a little bit too much. Overall, it's doing _much_ better, but something is still weird.

Bit of an update. The car had very little gas after all this work since January so I took it out today knowing it would likely stall again but thinking maybe it would last longer.

It died as expected. Got some logs at the time and it's the same **** really. Interesting thing is while it was hot and in a no start condition the vref held a solid 4.92v whilst cranking. After enough cool down time I was able to get it to start and idle. Measured again and vref was fairly solid at 4.92-5.00v. I haven't seen vref that solid at any point when running prior to this last batch of work.

I'm still getting .4-.9v on the power ground (positive probe to block and negative to better neg) when at idle.

I decided to bite the bullet and just order a replacement CAS to see what happens. I found some chatter on the DSM forums about this sort of failure (dying when hot). I can return it necessary.

I suppose it should come as no surprise that firing the parts cannon in an act of desperation based on some Google searching didn't work. New CAS and same story as my last updates.

IIRC, you had a log of your original failure where the MAP sensor just got stuck at a high value, which I assume flooded the engine. For the CAS, you can look at "Lost Sync Count", and "Lost Sync Reason" in MegaLogViewer to see if the CAS is mis-behaving.

Your latest measurement of 4.92-5.00 Vref is OK. The 0.4 to 0.9 on power ground is a bit much -- have you walked your meter probes along the power ground wire&connections to see if the loss is distributed or if you can pinpoint it?

Any recent logs that happened to capture misbehavior?

Well good news and bad news. Good news is I figured out I, for some reason, bought non-resistor spark plugs for this when I first started the build. Nice new set of resistor NGKs and I've got no voltage at my ground now. My VREF is pretty steady now but periodically it will drop a couple tenths. Idle is kind of weird on the car as well...I do need to verify base timing again on it since I've had the CAS in and out.

So I let it warm up. Everything looks good. Idle gets much better, VREF is hardly ever fluctuating, and nothing at the ground so I take it for a spin. Car is seemingly running great. I'm not going too crazy since I'm in my neighborhood but its pulling pretty nice. Nothing weird until it cuts out for maybe a second...like a quick hiccup. I figured it was the end but the car was fine. A minute or so later the 244 once again asserts dominance and leaves me on the side of the road to reassess the meaning of life.

I've got a log of it idling warm then driving and dying. Another of a restart attempt that was cut short because my laptop is ****. I'll look at them tomorrow or maybe the next day. Mentally drained right now.

bobxyz said:

IIRC, you had a log of your original failure where the MAP sensor just got stuck at a high value, which I assume flooded the engine. For the CAS, you can look at "Lost Sync Count", and "Lost Sync Reason" in MegaLogViewer to see if the CAS is mis-behaving.

Your latest measurement of 4.92-5.00 Vref is OK. The 0.4 to 0.9 on power ground is a bit much -- have you walked your meter probes along the power ground wire&connections to see if the loss is distributed or if you can pinpoint it?

Any recent logs that happened to capture misbehavior?

Click to expand...

Looks like I was posting my last response when you did. I've got a few logs from last week and this evening:
https://drive.google.com/drive/folders/1ab0P8letfjHofUqVCPQidJhoM2f8WUve?usp=sharing

So I left out in my last post that I did replace the CAS and there was no difference at all. This was before my realization of the spark plug issue brought up by a couple guys in the TB discord.

Today I tried isolating the WB again to rule out a suspected shorting controller causing all this. No difference.

I did make an interesting discovery today though with the help of the discord guys. When in a no start condition after the MAP pegging I'm getting around 4.8v on the MAP signal wire with key on. If I plug that into a spare MAP I have it drops to 1.5ish. Plug back into the old MAP and goes back up to 4.8v...however if it sits long enough the old map will go back to 1.5v as well.

Seems like a heat related MAP failure, however early on in this adventure I tired a new MAP and the same spike/death issue happened. I've got my MAP mounted to the intake manifold brace so it's really not in an extreme heat location. I've triple checked the connector and terminals...everything is solid and tight.

Since it's cheap and easy, I'd mount the MAP sensor in the cabin, or at least on a fender, well away from the engine heat. The extra few feet of hose won't make any difference (pressure waves travel at the speed of sound).

Are you happy with the electrical noise / Vref measurements now, or do you have lingering concerns?

bobxyz said:

Since it's cheap and easy, I'd mount the MAP sensor in the cabin, or at least on a fender, well away from the engine heat. The extra few feet of hose won't make any difference (pressure waves travel at the speed of sound).

Are you happy with the electrical noise / Vref measurements now, or do you have lingering concerns?

Click to expand...

I'm a little concerned with the vref dropping a bit but I'm not sure if that's normal or not? I'm very happy with what I'm seeing as far as grounds being voltage free and the massive vref spikes gone. Kicking myself on those plugs.

It seems easy enough to move the map over to the area behind the left shock tower below the fuel filter. I guess I can just do something temporary over there to see what happens. It's just odd because when I got it to die sitting on my driveway the heat in that area wasn't bad at all. I can grab the manifold support it's bolted to and it's not super hot or anything....and with it idling with the hood up it's not getting hit under the hood.

Great success today. Temporarily mounted the replacement map I had to the master cylinder hard lines and took it for a spin. Didn't stall so decided to drive it about 20 mins down the road to run some errands. No stalling. Ran a few more errands with lots of driving in this heat and the car didn't miss a beat.

So this week I'll be rerouting my map wiring over to the driver strut brace area and mounting it with the vacuum port facing down off the brace.

I still don't understand why the car still had the issue with this same map (although it was mounted to the manifold brace like before) like eight months ago then be fine now mounted elsewhere. Although looking back I never did drive the car with the new map since the vref and everything was still off the chart at idle. Maybe the other issues caused the original sensor demise?


So it appears this long road of troubleshooting has come to an end. Wish I had a definitive answer as to exactly what the problem is but I'll take this little win for now and just blame it on a bad MAP, some funky grounds, and the wrong voice in plugs. Thank you all for the help.

Great, I love happy endings.

One more thought on the MAP sensor - it might be a vibration problem and not heat. Inside the sensor is some sort of mechanical structure to sense the pressure, and maybe it doesn't deal well with engine vibrations.

bobxyz said:

Great, I love happy endings.

One more thought on the MAP sensor - it might be a vibration problem and not heat. Inside the sensor is some sort of mechanical structure to sense the pressure, and maybe it doesn't deal well with engine vibrations.

Click to expand...

I think you are right with the vibration factor and perhaps that becomes more of an issue with the aftermarket stuff that people say tend to fail prematurely. That first one was an AM unit from DIY.

Wanted to throw an update in here in case anyone runs across a similar issue...

So after discovering the fix I decided to place the MAP in my glove box. It had been suggested before and I figure you can't really get much more isolated from heat and vibration than in the glove box. I also couldn't find a mounting solution of my liking under the hood (with what I had on hand) to keep the vacuum inlet pointed downward. So I grab some more vacuum line from the store, wire everything up, and finish up the final stages of the rest of my wiring. Fire up the car and it's barely idling, loping like crazy, and running about 90kpa per TS. Figured maybe the vacuum feed was pinched somewhere. Check that out and no problems. Seems like a vacuum leak. Did some spray testing with brake cleaner and didn't find anything. Wyatt suggested maybe it's still the vacuum line and it's possibly too soft and large. I can't find any 3/16 or 5/32 vacuum hose that isn't garbage around here so I went for some stiffer 1/8" ID micro fuel hose from Lowes. That fixed my problem. I guess the hose I bought was collapsing under vacuum.

Long story short...vacuum hose quality is vital on these longer runs to the MAP. I think the fuel line may be decent enough as a permanent solution but I'm either going to get a nicer quality stiffer silicone or maybe bend up some hard line for part of run.