Dulvalius

2014 LT1 A6 cam car. Just got the cam install. Has headers and cai. I recently had some remote tune problems where the tuner couldnt get drivability correct and wouls stall out on decels to a stop and or blip on the throttle at low parking lot speeds.

Fast forward, i found a local tuner who dyno tuned it and fix the drivability problems. On 93, car made 488 wheel. When i went tonpick it up, everything was good and right b4 i left to drive home, he mentioned that cylinder 6 was running about 100 degrees hotter then the rest. Then asked me what sparkplugs i was using and how new they were (about 200 miles on them with new msd wires. NGKs TR7ix). He said it was most likely a missfire problem?

So after all of this, now a new problem...ive read that what would cause this would be more of a injector problem then sparkplug?

What do you guys reconmend i should do?

douniasg

How is he measuring individual cylinder Temps? I am about to purchase 8 egts to do this. If there is another way I would like to know. Thanks!

Dulvalius

A really good Laser gun of some sort id amagin? He said the insteument but it was something i never heard of so dont remeber.

ss2z06

you can buy a laser temp gun for $25 at a lot of places

C5 Diag

If cylinder 6 were misfiring that cylinder would be running 100 degrees cooler and not hotter due to lack of combustion in that cylinder...your tuner obviously doesn't understand basic engine fundamentals... I would look at a lean air fuel mixture possibly in that cylinder...maybe injector related...if diagnosing misfires is beyond your capability find a diagnostic shop in your area...not a general repair shop or a dealership...they will only replace parts until it's fixed !!

Dulvalius

Yeah i did a little diggin and it seemed you are right on the injector might being the cause instead of a sparkplug issue. Im gonna double check the temp when my laser gun comes in and take it from there.

Buddy A

try swapping injectors around and see if the higher temp follows the injector

Dulvalius

Yeah i Think ill just get a new injector if i go through the trouble of taking off the intake manifold and the direct injection lines.

C5 Diag

Just remember you’ll need some special tooling to replace these GDI injectors…they are not just plug and play !!

Dulvalius

So i got my pyrometer laser gun and went out and let it idle for about 20 mins. Took multiple temps at the same spot possible and it looks like #4 #6 #8 (passenger side) are running a little hotter then the rest. I was getting:

#8: 480-520. #7: 380-450
#6: 480-520. #5: 350-400
#4: 450-500. #3: 350-400
#2: 350-450. #1:350-400

This is kinda a rough average, every slight movement down the tube would result in different temps.

Is this even something i should be concerned of?
anyone with longtube headers maybe compare with my test?

C3_ERROR

I would be worried if it were me. 120degs between 8 and 1 it a lot. If it were me my first step would be to pull the injectors and have them cleaned. And while you have to intake off check to see if the fuel cross over tube is belt or crimped. That could be the cause of the passager banks running lean. And don't count out the plugs completely. If they are gapped too wide you could get the spark to blow out causing fuel to not burn completely. Meaning you might not have 3 hot cylinders, you might have 7 cold ones.

Dulvalius

Good info. I dont think the x-over tube is bent or pinched. The sparkplugs have abiut 200-300 miles on them and i remember gapping then to .040. But yeah..maybe a fresh set of plugs and injectors may do the trick.

Internets_Ninja

I would close the gap on those plugs to .030 and if you are using stock plug wires, change them out for the MSD's. It's very unlikely that you have multiple injectors having issues unless you had some sort of engine failure prior.

What is your Lambda at idle when you are taking these temps? 93 octane or Flex Fuel?

Dulvalius

They are msd wires already.
I just got it back from the tuner, i havent did a WoT pull yet cause of weather, but he said on the dyno was hitting 12.7 wot. Cruising home (50 min drive) highway and the wide band read 14- 15s bouncing around. However the wideband is in bank 1. 93 octane
Driving around, it doesnt seem to show signs of anything. Fuel is good.

Internets_Ninja

Next thing I would look at is the datalog of how the O2 sensors are behaving. A failing or damaged O2 sensor could cause one bank (2,4,6,8) or (1,3,5,7) to idle richer or leaner than the other side. This could account for the variance. I personally don't think 100 degree variance is that big of a deal on a cammed car. Check your O2's and check for any pre O2 exhaust leaks. I wouldn't stress too much about the comment made.

It would have been insightful if you could have measured the temps right after a dyno pull or while on the dyno in cruise mode. If there was a large variance in temps with this, then I would start to dive deeper. Otherwise I'm not too sure I would be concerned.

A few things could cause temp variances but they would be more extreme at WOT. Bent pushrods, poor sealing valve seats, broken valve springs, failing spark plug, failing coils, O2 sensor, exhaust leak, clogged injector, hurt piston rings etc....But my point here is, seems unlikely that you have any of these issues if the car drives great, you have good oil pressure, no misfires, and no noises.

Dulvalius

Thanks for the info. When it gets a little warmer ill put the car on the quick jack and look into all of this.

Cordes Performance Racing

You mention TR7ix plugs. Is it the long thread one's? Part number 6510 or part number 3690?

Dulvalius

6510s

s346k

i would not worry about the header primary temperatures. i would start by installing LTR5IX-11 spark plugs and gapping them ~.040. then i would try to recreate the misfire.

i had 2 injectors go bad on my camaro. the car would drive perfectly fine until wot & then it would (lean) pop and misfire. the datalog did not show a cel, misfire or anything funky with the injector timing/fuel use. wideband was rich while it was popping off and it clearly had a problem accelerating. the spark plugs told the story when i removed and inspected them.

edit: i bought some used injectors and replaced the 2 bad ones. installed new fuel lines under the manifold, no issues after that.

Dulvalius

I just installed some brisk rr15ys spark pspas and gapped them around .38-.40. Also did a compression check. Checked out good. All the cylinders are at 210. Buttoned back up. Started it up. It ran rough, even stalled on me revving it. Idk it was because i didnt prime the fuel line (had to disconnect my e85 line to reach spark plugs). Fired it back up, let it warm up, started missfire CEL (i could hear it), tryed to read it, but got nothing. So i cleared the code. Put about 15 miles on it watching the wideband and it seem to drive normal.
I think my next step is to put a smoke machine to it and new msd wires. I checked the exhaust temps when i got back home and they were about the same. Even cylinder 7 was kinda low (250 ish degrees). Fired it up the next day cold start and seem to idle fine.