lean condition on restart

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Spawne32
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lean condition on restart

Post by Spawne32 »

Hey guys, coming to you for this one. Ive been having this issue for a while now but it didnt turn up to be a problem until i went for inspection here in NJ. Car is a 1995 acura integra (automatic) with a JRSC supercharger with the stock pulley system, custom velocity stack shorty intake, rmf narrow header fed into a 2.5\" exhaust, mildly hand ported LS head, with a methanol injection system. Ive gone through the following solutions in the past month... - new walbro 255 fuel pump - new interstate megatron battery - new alternator from maniac electric - new 2awg ground wires - new AEM adjustable FPR - resoldered main relay for dry joints - new spark plugs/wires - new ignition coil/rotor/dizzy cap - verified that no fuel is pulled when hot in ectune Basically, its as follows, star the car cold, car runs great, drive around with no issues, if i sit in traffic long in the heat, the car will slowly start to lean out and misfire while sitting, push on the gas pedal, car goes back to normal. This happens consistently. Similar story, drive the car around on a hot day, stop at a store or something, 10-15 minutes, come back outside restart the car, car is missing and idling at 16+ afr, beat the piss out of it real hard, car goes right back to normal just fine. Turn car off, let it sit couple minutes, turn it back on, same thing, beat the piss out of it, car is fine. I have not been able to find a single cause for this issue at all, i have added fuel to the ECT fueling table so that it progressively has a + fueling condition up until 170 degrees, ive tried running closeloop, which will compensate for the lean condition, but does not make the misfire go away at all when this problem is occuring. Now, i did the ignition coil today, still getting the same problem ,but the new coil seems to have helped with the miss alot, ive getting better throttle response, and power output, but still having weird lean condition problems. Dont know why. I did a datalog of a warm start and basically what you will see is, the car will start up fine, lean out progressively till the fans kick on at 180, then all of the sudden go back to normal. I cannot find anything that changes during this time other then the ect fueling that adds up until a certain operating temp, and i dont know why the afr changes so much when the fans kick on from lean to normal. Towards the end of the log i throw the car in reverse and drive, then back in park, and let it level out.
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thething96
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Post by thething96 »

I've also had this issue with my car for a long time, just never thought too much about it. But I'm having the exact same problem. I have a feeling that the iat is soaking up a lot of heat, and maybe the iat fuel compensations have to be tweaked to a \"certain extent\", I wouldn't know to what extent. It does get annoying from time to time.

Spawne32
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Location: NJ

Post by Spawne32 »

Did some more stuff the other day, my breather filter on the vc was clogged completely, i was unable to fit the pcv valve and such in on the crankcase vent system so its been open since then, but it wasnt breathing at all, i put a dump hose on it and its venting a shit ton of pressure out of the house when hot, it seems to help with hot starts immensely. Only got as lean as 15.6 afr today on a hot restart, one thing i noticed is that when this does happen, my low end boost afr goes from 13's to high 11's afr wise for some reason, no idea what would cause to to be rich anywhere else except idle when this problem is occurring. All i know is its driving me fuckin insane.

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TopMountGSR
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Post by TopMountGSR »

Relocating your iat before the tb helps Also using a gm iat sensor helps as well, as it reacts faster. Add fuel in your iat comp tables in the light load column when the iats rise. This will solve the lean condition when you idle for an extended period of time. You will never be able to tune out the hot start temp lean condition. It happens with bone stock hondas. When you use the gm iat, this lean condition time frame shortens.
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TopMountGSR
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Post by TopMountGSR »

Also be prepared to have problems out of that aem fpr.
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Spawne32
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Post by Spawne32 »

i keep the IAT in the intake manifold because it gives me better control over the blower temps since im using methanol as the basis for cooling, putting it in the intake leaves me with no idea how hot im getting and when. If the GM IAT will swap into that factory position on the manifold ill gladly make that switch.

Spawne32
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Post by Spawne32 »

follow up here, as i was telling 9400rpms this morning, i went to go pick my buddy up for lunch at his work, car drove great going down there. Picked him up went to pizza hut up the street, car sat for about an hour. I went back outside started the car up, car was idling at about 17afr, running like crap, so i went and dropped him back off, car leveled out good, but the whole time going home it was rich as hell under boost, 11.4 or so figuring at 1psi @ around 2500rpms, typically at this point it would be around 13afr at this low rpm. I have IAT based reductions for when the car gets really hot, and its really really hot out today, but how much do i need to reduce before i start having a problem? Based on what i saw today i made the following adjustments, raised the last two post start columns up slightly in fueling, then did a few more reductions in IAT based corrections. Image Image

Spawne32
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Post by Spawne32 »

the numbers in red are what the previous values were while driving today

Natural Aspirations
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Post by Natural Aspirations »

Have you corrected your injector battery offset tables like I have been trying to tell you to do?

Spawne32
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Post by Spawne32 »

at least 10 different times

Spawne32
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Post by Spawne32 »

ill go over them again tonight just to make sure again lol

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TopMountGSR
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Post by TopMountGSR »

That's exactly what I am talking about. You need to add fuel in the light load high iat temp areas. You will never fix the temp lean condition you see when you start a car that was just turned off within the hr and is still hot. It will idle lean for 30 sec to a minute then go back to your normal fueling. If you put a wideband in a bone stock honda, it does this. So I accepted it a long time ago. If you use the gm iat, before the throttle body, not in the intake mani, it will reduce this lean condition on hot restarts some. Your tune will also stick longer and the iat sensor is less prone to heat soak. The gm iat wont go in a stock iat flange, its a threaded sensor. I found a nut that it threaded into, and welded it into the charge pipe like a 02 bung. Its an open element sensor so it reacts faster than a stock closed element iat sensor. Also supercharged setups are a bit different, we normally try to leave the sensor in the manifold because its closer to actual charge temps seen by the engine. However we have still done supercharged setups with the iat relocated in the intake. All the turbo setups we build, we relocate the iat in the charge pipe before the tb. Na setups we put the iat in the intake.
DKGoodrich EFI Tuning Solutions eCtune Authorized Tuner Frankfort, KY, U.S.A. 859-421-3334 http://www.dkgoodrich.com Image

Spawne32
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Post by Spawne32 »

i get what your saying, but the issue is the IAT isnt what causes the lean condition when it restarts, ive checked this multiple times, the IAT actually decreases after it sits, thats why i cant determine the cause. The way i have the IAT tables set is by what i see when its hot out, as it progressively gets richer the hotter it gets, i can see this even at idle when moving through traffic. Ill use a GM threaded IAT sensor if i can manage it, but i would still put it in the manifold because again, this is essential to me to keep those temps monitored, thats the whole way i setup the tune, but will the GM sensor be able to handle methanol being open element or will i have to look into using a bosch instead.

Spawne32
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Joined: Sun Sep 19, 2010 1:51 pm
Location: NJ

Post by Spawne32 »

well, hundred plus today, with the new values in place, car just continues to get richer as it goes, hotter it gets, richer its getting while driving, leaner it gets at idle after the restart, weirdest thing ive ever seen in my entire life.

Spawne32
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Post by Spawne32 »

also, started to get overly hot coming off the highway, probably around 215-220, my overheat protection kicks in at 225 which throws a check engine light and rev limits the car, that didnt happen but i was getting to the dead center of the gauge, maybe slightly over, until i came to a stop in the shade, then it slowly started to go down. additionally, it seemed to be getting richer under boost (because its easier to notice while in boost as that area is tuned smoother) the higher the gears got, so i would be in the 12's afr wise at say...2psi @ 2500rpm, and then id get into 2nd and it would be like 11.6 and then third would be like 10.5, just progressively worse as it went up, mind you this only occurs in the extreme heat.

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