problems after h23/a6 intake swap, lean condition

[DunKrS]

I swapped in a hybrid a6/h23 intake manifold a few months ago and have had really bad drivability problems since.
I have a pt6 ecu, double stacked iabs one is gutted, wired in with black box. 65mm prelude type s throttle body. cleaned egr ports. calibrated tps properly smooth sweep from closed to wot.

wideband says idling around 16.8-17.2:1. wot is around 15:1. it pops and backfires into the intake from stopsigns sometimes and it hits around 19:1 afr when the popping occurs.
I have no CELs and have tried different map, tps, clt and even bought a new denso o2 sensor. Wanna put my delta 272 and dc header on but I want to fix this issue first.
Have a chipped p06 with iab mod from xenocron but it runs similar afrs.

Somone suggested IAT sensor.
Car is in very good mechanical health and ran and drove fine before, although i didn't have the wideband to see the AFRs before I swapped the intake. it would hickup from stops on rare occasions but never backfire into the intake manifold prior to the swap. idles at 750 but shudders and shakes as soon as you turn on headlights or A/C or roll windows down which I think makes sense with such a lean idle ratio.

[GhostAccord]

Backfiring through the intake is usually a sign of a mechanical timing or a valve lash issue.

As far as the lean condition that could also be attributed to a timing or valve adjustment issue.

Those mods shouldn't lean out the stock injectors that much. Do you have your stock O2 sensor operational?

If your timing and valves check out you could look at upgrading to a set of larger flowing injectors. Take the AFRs that you are seeing and determine a % increase that would best suit them. That is how I had my 2.0L zetec running, I saw an increase of 20% on my long term fuel trims so I added 20% larger injectors. Now my car runs at stock AFR and fuel trims.

[8ball]

Silly question but did you reuse gaskets? Are your ground good? Silly question but maybe your spark plug wires are crossed? (it can happen)

[DunKrS]

I adjusted the valves and did the timing belt 2000 miles ago. cam and crank pulleys line up properly still. plug wires are where they should be. I was worried i got a california model pt6 and maybe it was set leaner so the manifold was too much but after checking that out it is not california spec ecu. (whether or not that is plausible idk, makes sense in my head that an ecu that was already set lean would have no wiggle room for a manifold that flowed even more air)

I guess my next guesstimation/hypothetical proposition is
If the iat was calling out hot air to the most extreme number that was still in spec would it not throw a CEL but still lean out the injector pulse width enough to achieve those kind of AFR numbers? It's the only sensor I have yet to change out with a known good sensor or replace.

I had a set of dsm 450s and threw those in to see if maybe the chipped ecu got set for 450's and not stock injectors like i specified but then it was 9 and 10:1 afr lol so no go there. and the stock ecu runs similar numbers so my guess is the basemap on the chip i got from xenocron is pretty close to a stock map and probably not the problem.

maybe i got some magical h23 plenum or a6 runners and they flow just perfectly so i am getting more air than anyone ever before (bahahaha) and my ecu's just can't hang with the intakes majesty. maybe a tune will show which parameter is out of spec or the tune itself will solve this issue. i'm at a loss though at this point. i ordered a basemap chip for the delta272 and dsm 450's though because i plan to use those when i get tuned.

sidenote. unplugging the clt sensor put my afrs around 15:1 idle and 13-12.7:1 WOT and the thing pulls hard and doesn't backfire or sputter anymore. i have tried several different clt sensors and they all run the same until i unplug them. But the car will not start in the morning so i have to plug it in, start it, warm it up, then unplug it and it runs good but this is very annoying.

[GhostAccord]

If your mechanical timing and valves are good then it could be a sensor issue changing electronic timing.

By CLT are you referring to your coolant temperature sensor? Could be out of range and need replacement if it works better with it unplugged.

Have you adjusted the throttle stop or throttle adjustment screws at all?

Are you still running the IAC and FIT valves?

[DunKrS]

That's what I'm thinking. I have replace as well as tried several different coolant temperature sensors all with the same results.

Throttle stop and idle adjustment screws are untouched and still have the factory paint marks on them

IACV is in place but the FITV is eliminated.

[DunKrS]

put my delta 272 in today with a basemap from HA Motorsports. Not a surprise to me or anyone else it doesn't idle and this new basemap runs worse than anything i've tried so far. a stock p06 actually runs my car better than my basemap from xenocron or the stock ecu does. it runs the delta pretty well other than it won't idle. it still has the most consistant afr's. and the afrs were around 14.7 at idle before the cam swap today.

I am lost. my tps is at .45v closed and 4.6v WOT. I adjusted the valves and checked the timing on the timing belt while installing the cam and those are both fine.
I tried another intake air temp sensor and that didn't change anything. The coolant temp sensor has been changed with both a new sensor and a used known good sensor with no change. ignition timing is set as per the factory service manual. plugs, wires, cap and rotor are new.

It was my understanding that people put h23 plenums, a6 runners, double stacked iabs together and ran them just fine with pt6 ecus with no issue. that is where my problems started. the popping and backfiring and stuff started with the swap.

am I just gonna need to take this to a tuner and have them tell me what is wrong once they can see sensor inputs?

[GhostAccord]

You need to see sensor data.... I'd like to see how much vacuum you are pulling at idle. If you had an issue at idle on stck cams, dropping a set of long duration/overlap 272 cams isn't going to help the problem. There sounds like you may have a MAP/vacuum issue and an engine temp issue.

Best to have someone hook up to the chipped ECU and see what the sensors are telling you. Specially before you start throwing more parts at this.

[wagon-r]

It was my understanding that people put h23 plenums, a6 runners, double stacked iabs together and ran them just fine with pt6 ecus with no issue. that is where my problems started. the popping and backfiring and stuff started with the swap.

am I just gonna need to take this to a tuner and have them tell me what is wrong once they can see sensor inputs?

H23 intake is not going to change air flow very much at light loads and lower engine rpms. Thus, your problem is NOT the intake. Rather, something happened with sensors, fuel injectors, or wiring during the swap. So, you need to get it fixed. Likely doesn't matter if you take it to a tuner or a good mechanic - they just need to find out what the problem is.

[DunKrS]

Thought I'd follow up with this. Sensors all read fine. went and got a street tune and car runs great now. for whatever reason my ecu was just not throwing the right amount of fuel at it and was running super lean.

[DunKrS]

I swapped back to an a6 cam and pt6 ecu and this problem is back now. Dude who did my street tune wasn't very knowledgeable and although my car was pretty fast and consistent on afr's it was a bitch to drive at low speed and he spent no time tuning part throttle.


I am so lost on this thing. this ecu should run this setup no problem I thought? but no matter what at 3800 rpms it will drop from 14.5-15.1 afr to 18-19 and with that comes a change in engine sound and a very noticable drop in power. I have now tried 3 different o2 sensors 1 used NTK and 2 brande new Denso sensors, 2 iat sensors and checked their readings at the ecu plug, 2 used oem coolant temp sensors and one brand new one and checked it at the ecu plug as well. I have a map mounted to the throttle body as well as the map in the black box and they both behave the same way.

I cleaned the ecu ground at the thermostat housing and it seems to run smoother, and sometimes it'll drop afr's like always but slowly start creeping from 18 down to around 15 (which runs okay but is still pretty lean and still just dumps from stoich to 18-19 at 3800) before I have to shift from 3rd to 4th or 4th to 5th. I figured if cleaning it did that then adding a whole extra ground would help. So I added another ground wire from the ecu ground at the thermostat to the chassis but there was no change. it runs the worst when the car is hot and I shut it off to go somewhere and come back. like the heatsoaking that goes on definitely is a factor. I want to get hondata or neptune so I can see sensor parameters so bad but school has me strapped for cash.

Anyone have any suggestions? getting on the freeway and up to 75 sucks when you're basically forced not to rev past 3800...

[djcaz_aom]

Have you chevked for vacuum leaks? Is it possible that the IAT plug is plugged into the black box and the IAB connector into the IAT? Where is the gutted spacer located? How did you gut it? Is it open all the way or you just eliminated the butterflies?

It sounds to me like something you did during the manfold seap caused the problem. Why not go back to stock and start from there?

[93redcb7]

all of your problem is fuel(or most of it), you change the injectors it goes way to rich. the ones that are in it are running it to lean when it requires more fuel. What I would say to do is either get some good injectors from the JY and have them cleaned and flow balanced, or throw the DSM's in and have it tuned with all the mods you have. running a chipped ECU with SET fuel/timing maps isnt good unless its specifically for your engine setup.

[DunKrS]

no vacuum leaks, iacv is clean and functions properly by upping the idle when cold and keeping the idle stable arou d 750-800 rpms or so. and the iabs open around 4k like they are supposed to. I took the butterflies off the shaft and took the shaft out of the spacer and filled all the holes for the shaft with jb weld and then sanded the excess jb weld till the holes were smooth. At this point the only thing I can think is despite everyone else having a grand old time with this swap for whatever reason my car is special and my manifold flows too much air for the stock ecu to keep up with. which makes no sense as according to some tech info I read on hondata's website the stock ecu can deviate 30% in fueling from the programmed tables. so I'm assuming 15% above factory tables and 15% below. 15 percent more fuel could provide for 15ish% more horsepower so long as the fuel curve is similar. which I suppose it may not be in my case. I'm saving up for a hondata or neptune. but I've read multiple threads where wagon-r and others discuss at length that this setup runs fine on a pt6. I suppose injectors could be an issue but the fuel filter is new and I have tried injectors from another car in here and it still ran the same while the other car runs fine with them. I should mention that anytime before 3800rpms that if I exceed about 80% throttle it will drop to 18-19afr as well. Does anyone know what set of conditions call for open loop? maybe the open loop table is really my issue and > 80% throttle and or >3800rpms activate open loop and cause my issue? Can anyone confirm or deny this? if this is the case then why are others not complaining of this issue? I'm almost thinking about wiring in a potentiometer in the cabin to the coolant temp circuit so I can artificially richen the mixture when needed.

[93redcb7]

no vacuum leaks, iacv is clean and functions properly by upping the idle when cold and keeping the idle stable arou d 750-800 rpms or so. and the iabs open around 4k like they are supposed to. I took the butterflies off the shaft and took the shaft out of the spacer and filled all the holes for the shaft with jb weld and then sanded the excess jb weld till the holes were smooth. At this point the only thing I can think is despite everyone else having a grand old time with this swap for whatever reason my car is special and my manifold flows too much air for the stock ecu to keep up with. which makes no sense as according to some tech info I read on hondata's website the stock ecu can deviate 30% in fueling from the programmed tables. so I'm assuming 15% above factory tables and 15% below. 15 percent more fuel could provide for 15ish% more horsepower so long as the fuel curve is similar. which I suppose it may not be in my case. I'm saving up for a hondata or neptune. but I've read multiple threads where wagon-r and others discuss at length that this setup runs fine on a pt6. I suppose injectors could be an issue but the fuel filter is new and I have tried injectors from another car in here and it still ran the same while the other car runs fine with them. I should mention that anytime before 3800rpms that if I exceed about 80% throttle it will drop to 18-19afr as well. Does anyone know what set of conditions call for open loop? maybe the open loop table is really my issue and > 80% throttle and or >3800rpms activate open loop and cause my issue? Can anyone confirm or deny this? if this is the case then why are others not complaining of this issue? I'm almost thinking about wiring in a potentiometer in the cabin to the coolant temp circuit so I can artificially richen the mixture when needed.

2 other things to check, are TPS and also did you happen to reset the ECU?