First things first. This happened this weekend after trying to get the car tuned. I'm not pointing fingers at the tuner or shop nor will I name them. This thread has nothing to do with the tuner, i only reference the ROMs so it can be understood what was done.

03 g35
vortech 2.87
cjm return fuel
pauter rods
arias ED 9.5:1 pistons
arp mains and L19 headstuds
hks gasket
tomei cams
completely ferrera valvetrain


sidenote: CIPHER_4-3-2010_10-15-32_PM.csv (and session 1 of logworks) is the first saved log: old ROM, map 3. didn't really do anything with this, hit the button on accident.

i named each session in logworks the same name as the corresponding file in cipher so it would be easy to find.

After it looked ok on some small things watching afr in logworks i did a long pull that was logged. CIPHER_4-3-2010_10-15-58_PM.csv (session 2 logworks) is the file it was on Old ROM map 3 (previous map). Timing was low, afr was low. I made a few adjustments to map 3 prior to this run and i liked the outcome so i saved the RTT. Pulled over and loaded the updated RTT to map 3 and flashed the car.

Started back off. Forgot to switch maps on the car so i was in Old rom Map 1 which is a map i loaded from new map into my old rom. I did a full pull with it while i logged everything. CIPHER_4-3-2010_10-33-12_PM.csv (and session 3 logworks) are the files. Timing was really high and i glanced at this after the pull. That's when i realized i wasn't in map 3. I switched over to map 3 now which is the map i did the other pulls on. *for those not looking at logs the map put me about 28 deg timing all the way to redline with up to 12psi boost from vortech. low 10:1 afr

Final pull, Old rom, map 3. CIPHER_4-3-2010_10-34-24_PM.csv (session 4 logworks). You can see right around 4300rpms there is a quick drop in rpms. That is the area i heard the loud pop. I pulled the car over and the engine temps were rising fast. The coolant resevour was full. I waited a while then started the car back up and it idled ok (same as it used to idle before). I didn't see smoke from the exhaust or smell anything in the exhaust. The coolant is green in color and i checked the oil and it was no milky. It was still golden and at the same level it was before. *this was 11-12 deg timing all the way to redline with low 10's afr.

My thoughts were blown head gasket and combustion gases into the cooling system causing it to fill up the resevour. The normal coolant, normal oil, no smoke, and no exhaust smell have thrown me off though. The next morning after getting the car back i decided to bleed the cooling system. Fired the car up and it idled and went to operating temp as normal. It sat and idled while i purged the cooling system and never went above normal operating temps. The heater was blowing hot so i know all the is out of the cooling system. The car was in the garage and there was zero smoke and no sweet smell at all. It sat and idled for about 10 minutes at operating temps without an issue. This confuses me about what happend.

My next guess is that maybe with the high afr and low timing (during the pull that popped) that the cylinders just got hot and i had a backfire causing the noise. The coolant in the res was just due to the increased engine temps and had nothing to do with the backfire.

Ok, i'm in STL and car is back in indiana. I didn't have any of my tools over there at the time when i brought the car to my garage. It's sitting there now. I'll go home after finals here in a few weeks and run a comp test and do the radiator gas test to see if i'm leaking head gasket. I just want an opinion on what could have gone wrong.

I'm hoping it's just a backfire. Maybe i left off a little as the tps shows right before the pop and with a 10:1 afr it could have loaded the engine adn backfired. I'm sad to think that the truth is the high timing run caused damage and the normal run did it in.

This sucks totally because i spend the money i budgeted for tuning this weekend and i don't have time to go home and fix my car. I definitely do'nt have cash to pay someone 10hrs labor to fix my head gasket if that's the case. I'm so bummed out right now because i'm seeing all my hard work falling apart right in front of my eyes. It will be 3 years til i'm out of med school and will have cash.


UPDATE

So I tore the engine down. I found a few places for small leaks and one major one. #6 cylinder had blown through even the metal portion of the head gasket between the cylinder and the water jacket.

I replaced that and fixed a few small things here and there and the car fired right up and so far is leak free. I haven't put it under boost yet. I'm wiring up some more sensors for my datalogger then i'll take it out for a few boost runs.

I'll get some pics of the head gasket crank here in a few.

 

sorry to hear about your troubles man. i'm also hoping it was just a back/misfire. from what i've read on headgasket issues, you'd see contaminants in your coolant & oil pretty quickly if that was the issue...as well as a windshield full of coolant.

 

So in the end, there are no problems?

 

well, in the end the car idles ok (not great, but the same as it used to)

coolant temp stays the same under idle

I didn't have time to take it for a drive or anything. My fear is maybe there's just a crack in the gasket and nothing would be noticed until the system is under pressure from driving or boost.

so rich, do you know of instances where it's made a noise like that and coolant been pushed out but no damage? I figured maybe the overheat caused the coolant to be pushed out since it wans't violently pushed out, it just filled the overflow but didn't spray out of it.

 

also, US 41 is horribly bumpy with my suspension...i was bouncing up and down a lot which is why i'm thinking maybe, just maybe the dip in tps noticed with the drop in rpms could have happened BEFORE the pop. Like if my foot slightly came off the accelerator then jammed back down and with that low afr it caused a fuel load then backfire.

So i've been told on the phone that with the low timing i was running and low afr the combustion temps would be really high.

 

if it was the head gasket.. there would be smoke, smell etc.. stuff youd see and know right away.

 

ya the coolant in your reservoir goes up and down. if it was anything more than a misfire or backfire, you'd prolly have other symptoms

 

so, i shoudlnt' be laying in the fetal position on the floor hating myself yet?

The drop in rpm on the log corresponds to a dip in TPS which pushes me towards accidental let off of throttle which loaded the hot chamber with fuel then when my foot went back down it backfired. It only dipped for .4 second based on my logs. At that point logworks says that i only dropped from 4210 to 4150 (70rpm). That could have easily been a bounce of my foot right?

I'm driving myself nuts not being able to test it. I might see if one of my buddies from back home can key into my garage and do a combustion gas test on my radiator for me. The only problem i'm worried about is can the head gasket be sealed at idle but then leak at higher rpms? if that's the case then the gas test would be invalid i think. I guess they can do a compression test also since i just did one the day before the tune. compare the numbers before and after.

So if those both check out would it be safe to say it's normal and i don't have to do a tear down?

 

You are using Osiris right and were you road tuning? I thought Osisir dont have support for 3rd party WB so you are tuning using your OEM 02 sensor?

 

i log in cipher and i also use my laptop to log my innovate wideband and auxbox. So 1 log is cipher and the other is logworks.

I was making adjustments since no boost or anything was done to my car by the tuner.

 

I think its just a backfire man.. I know the kind of POP your talking about.. when I had the vortech and I would use WOT box.. no lift shift feature.. I would get the same pop. I just think ud know right away if your headgasket blew... either your cruising around town or your going at it...

 

I'm sending some buddies to my house to do a leakdwn this friday.

I'm stressing big time. I hope it's not blown or I'll have to think real hard about putting the stock engine back in when I pull this one to fix it. I don't have time for it in the next 3 yrs. I've felt like throwing up for 2 days straight now.

 

The overfill tank level goes up and down, but not drastically. On my cars stock motor (vq30), normal driving out of boost or less than 7psi there were no issues. As soon as it got 10psi, the combustion pressure would leak into the cooling system. While going for a run I didnt have any symptoms, however when I would pull over and look at the overfill tank it was basically topped off with steam coming out, as well as the radiator hoses being extremely tight. I drove like this for about a year or more, till eventually it was so bad that it would literally blow up the radiator hoses.

Took the car apart, and it was the head gasket, was in real bad shape, but not enough to leak coolant into combustion.

So to a previous post, there dosent necessarily need to be smoke or smell when a HG goes bad or its leaking (because it can be leaking from cylinder into coolant passage and not vice versa). Also testing compression while having this HG issues resulted in perfect or within spec compression numbers, so HG can be hard to identify.

OP, to me what you are describing might just have been detonation or a misfire, I remember when I was trying to tune with higher boost, i was retarding too much timing and it was missing, possibly due to detonation since EGT was too high from the amount of timing being retarded. If your really worried about the headgasket, just check the level, when you get into boost if its bad it can force the coolant to go into the overfill tank, later on once the car is cooled down and sitting for a while, check your coolant level, if its not topped off then there is an issue.

 

Most likely culprit sounds like a backfire. They car be alarming if you aren't used to hearing it. Also, it seems you may have been running a little rich as well and this may have caused a fair amount of fuel to dump into the downpipe and ignite

 

ive never had a problem or backfire of any sort..idk...good luck...

 

Your head gasket is likely blown. When mine went the coolant overflow filled right to the top.

When the car cooled down it sucked back the coolant and under normal driving it was fine, when hitting boost it filled the over flow again.

There were no signs of contamination in my oil and the coolant look the same as well until i drained it I could see small traces of oil in it.

When i took the heads off I could see the traces carbon going from the cylinder to the water jacket. It seemed to reseal when not under boost and when under boost the pressure keeps the coolant from getting in the oil but pushes the coolant out of the block causing the overflow to fill up.

I had no other signs no noticeable smoke or anything else but my wideband got cooked from the coolant hitting it and the second or third pull when I was diagnosing I could smell the coolant in the exhaust. I also pressure tested the cooling system and it never showed any loss of pressure so it did take a few pulls hitting the boost and all of the coolant being pushed into the overflow to be sure it was a headgasket.

Sucks to hear but I think you popped a gasket

 

aw man =(

 

that's what i was thinking. My buddies are going to do a comp test, leakdown, and then a block test (for combustion gases in radiator). Between all 3 of those i'm sure something will have to be positive if it's a gasket leak. I'll have to think really hard about putting my stock longblock back in if it's the gasket. I really can't afford the time and effort at this point to fix the built block until next winter. It will only cost me half a day to swap the engines (which is all it took to swap them the first time).

damn it i wish dohc wasn't so freaking hard to change a head gasket. My buddy ryan that is doing the testing for me this weekend changed his LS1 headgaskets in under 2 hours while the engine was in the car.....

 

Hope everything turns out okay.

 

You're in the same spot I was in with looking long and hard at the stock block. All of the tests I did never showed any sign of head gasket issues it seemed to seal right back up again (I only went to 19psi about 4 times) but every time I hit full boost it pushed coolant. After testing it I thought I dodged a bullet then went and got in some boost sure enough pushed coolant

Good luck i hope you did dodge the bullet.