warrick

integra gs b20b, gt28rs, 450cc injectors, resistor box, crome using p72 codebase, advanced boost tools+.
ngk heat range 7 plugs, gapped to 30 thousandths
AFRs are fine, 10-12, timing is retarded using the step retard script.

checked timing, it's a solid 16 degrees. changed map sensor, checked TPS, checked wastegate, checked for boost leaks.

here is what happens...

the car is at full boost by 2800rpm, and pulls until 3700ish, and then it starts popping, and will sometimes backfire. when this starts happening, AFRs dip into the 10s. this will happen no matter how much throttle. the less throttle, the less violent it is, even if you're at full boost. if you go very light throttle, without building boost, there is no bucking.

I've played with injector settings, fuel correction, timing, duration.

I'll be doing a valve adjustment and checking the cam timing in the morning, but what else should I do? I need ideas.

LVB18Civic

Sounds like your car is going into "limp mode". Your map sensor is seeing boost pressure.

b18ccivics

what is your timming at under boost, does your exhaust gas temp go threw the roof,if it does advance your timming under boost, if timming id too advanced it will detonate and you can hear it, but take it easy start out at very low boost and work your way up before you need a new motor. it sounds like lvb18civic doesnt know what crome is

abnaasefmb

"When I was young and just starting out tuning engines an old man said to me "ninety percent of all your carburetor problems will be found in the distributor". At the time, I thought he was just a kooky old man. After years of tuning, my own experience seems to have proven him right. Many tuning issues with both carburetors, and modern fuel injection systems are mistakenly blamed on the fuel system.

One thing to watch out for when tuning an engine using a modern fuel injection system is false information from an oxygen sensor when an engine misfires.

When an ignition event fails to happen, or the engine "misfires", the oxygen sensor will want to read a leaner mixture than what really exists. This is due to the fact that the oxygen sensor can only read burned hydrocarbons. When the engine misfires, the unburned fuel doesn't get recognized by the sensor, so it seems that there is a large excess of oxygen in the exhaust system."
.........ben strader

warrick

I've tried retarding as well as advancing timing very gently, but there is absolutely no change..

time to check cam timing

JDMisGOOD

How much boost? Which map sensor?

blundar

Swap out distributor.
Why are you using P72 codebase? Crome is much less friendly to that - use P30.

SOHC_MShue

I am willing to bet the problem lies somewhere in your ignition system like they are all saying. I have had so many cars do the same thing when they had bad plug wires, something worn or burnt out in the dizzy, plugs gapped too wide, etc. After a closer look at the ignition it was always fixed.

warrick

I tried the p30 base and it didn't like idling at all, but I'll try again.

I'll try to get another dizzy.

.RTErnie

sounds like an ignition issue...like they said. Sounds like you're just loosing a TON of timing. check over your maps or post them up so we can see. has the car ever ran well before? Or is the first time its been boosted?

warrick

first time it's been boosted. I'll get the map up.

cam timing is fine, changed ignitor and coil in the dizzy, same issues.

here is the map
http://members.shaw.ca/w4rr1ck/johnny-test3.bin
here is a datalog from the beginning of the issue. it isn't as severe now, and it only happens >3500RPM.



yes, I know it's rich, but the issue happens whether it's 10 or 12 afr.. blue line is MAP, reading about 9psi. green is TPS, it's about 25-30% throttle.



Modified by warrick at 4:20 PM 10/11/2005

D@nnY

how much boost are you running? are they dsm injectors? you need to make sure the resistor box is wired right and check the resistance in the injectors . laso check the plug wires resistance whiel your at it

warrick

9lbs, yes, they are dsm injectors. we've tried blue and black tops. resistor box is wired properly, and injector resistance is where it should be (very few ohms).

old plug wires were in spec, and the ones we're using now are almost brand new nology's.

SOHCmaster

Does it sound like missing like a popcorn popper under full boost load.
Could be plugs are fouling out from city driving. Did you try a fresh set of plugs yet ? Sometimes this happens to me on a monthly basis.

warrick

it does sound similar to popcorn, but it's not detonation... happens under all timing conditions, all fueling conditions.

plugs are brand new, not fouled. city driving is a nice 15:1.

CoreyR

had the same problem with a turbo B16. ended up being the plugs and they didnt look bad either. happened every couple days after hard driving. just a suggestion.

splitime

Had something that sounds like this on a recent car... was the MSD plug wires... they kept popping loose and we kept basically having a cylinder getting intermitant spark.

HiProfile

I remember reading about wire technology not long ago. OEM style carbon wires wear out eventually, and nology style capcitor/shielded/grounded wires tend to break down. Something about induction, can't recall. Try a new set of genuine honda wires, otherwise check the coil.

If its not the wires, I'd look at the step retard. Take the time to calculate timing and plug the numbers in manually.

SOHCmaster

Do you have an adjustable FPR, improper setting can also cause symtoms like this.
just trying to think of things,

warrick

FPR is stock.

update:
checked the timing belt, it was very loose. fixed that, re-timed, same issue.

I loaded up a few different maps, played with timing, and the bucking got worse.

tried a different ecu, same thing.

I'm wondering if I'm screwing up somewhere with crome. does someone feel like making me a basemap?

SOHC_MShue

Look deeper into the ignition...i can almost guarantee the problem lies there.

b18ccivics

your log tells me nothing, log rpm, tps, afr, load preferbably in psi, and ignition timming.

warrick

it is there to present a general idea of the bucking without huge changes in AFRs

.RTErnie

what is the black line? Replace plugs, regap at like .022, replace wires. Lean your fuel mixture down to 11.5:1 And try it again. The black like is what? RPM?

warrick

yeah, black is RPM.

I'll try the plugs and gapping, and I'm trying to get a hold of of another distributor.