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[snm95ls]

The odd lean missfire at idle is getting under my skin.  I really didn't like the idea of running them with a resister box in the first place even though people have been doing it for years.

I just ordered a DIY P&H driver board from jbperf.com.

Hopefully all works out well.


Anybody on here tried one out?

[Joseph Davis]

If you can't get DSM 450cc to idle like butter a P&H driver box won't help you.

[Joseph Davis]

But, to answer your question, those are exactly the daughterboards I planned on using with the next set of 1600cc injectors I touch.

[snm95ls]

If you can't get DSM 450cc to idle like butter a P&H driver box won't help you.

Ok.


I'll just burn the motherfucker to the ground then.

[Joseph Davis]

You think they might be old injectors and not flowing so hot anymore?  Does the idle start popping when you turn the headlights on, etc?

[snm95ls]

You think they might be old injectors and not flowing so hot anymore?  Does the idle start popping when you turn the headlights on, etc?

JD, I had them cleaned and flow tested by Injector Rehab.

I notice it more when the outside temps are high.  To me that says that the small pulse widths needed for my particular combo do not mesh well with a shitbox resister pack and P&H injectors.

I could easily run in open loop all of the time and get to idle butter smooth with an ever so slightly rich A?F, but I am not interested in doing so.



It is a bone stock A6 in an STD, with a wire harness that I had to fabricate because of a botched MPFI conversion from a previous owner.

[Joseph Davis]

Hot IM can cause the fuel to fall out or evaporate to a different degree.  Add in what I am ASSuming is a one wire O2 and I guess AFRs at idle are going and getting themselves fucked.

Jared Deskins swore by converting the older cars to 4 wire O2 a decade ago, said it made the idle better and picked up mpg.  Maybe you should try that first?

[snm95ls]

Hot IM can cause the fuel to fall out or evaporate to a different degree.  Add in what I am ASSuming is a one wire O2 and I guess AFRs at idle are going and getting themselves fucked.

Jared Deskins swore by converting the older cars to 4 wire O2 a decade ago, said it made the idle better and picked up mpg.  Maybe you should try that first?

Forgot to mention it is a hard wired OBD1/MPFI conversion.

So no 1 wire oxygen sensor.

The A/F at idle is fine until the little lean missfires here and there.  The permanently installed WB shows these quite well as the A/F will jump to mid 15s pretty much in time with the missifre.

It is not a constant deal.  Just when ambient temps are above about 75°F.

I have not bothered to check IAT readings.

I guess the root problem could be ignition based, but I highly doubt it.  The only change in the combination has been the addition of the DSM 450s and a retune to compensate.

[Joseph Davis]

It's something in the fuel or ignition system, got to be.

[snm95ls]

It's something in the fuel or ignition system, got to be.

Dunno man.

The fuel pressure is within spec.  The maps do seem to be a bit oddly shaped to me, but I dunno.  I would upload the .bin right now, but I don't feel like booting up my tuning laptop to do it.

 

[patsmx5]

What gap are you running on your plugs? What heat range? And what's wrong with a slightly rich idle? Mine idles 11:1 till it's hot, then it's 12:1. I'm running 20* advance at 700 RPMs, 22* 1000 RPMs, holds strong vacuum, purrrrrrrs.

[snm95ls]

What gap are you running on your plugs? What heat range? And what's wrong with a slightly rich idle? Mine idles 11:1 till it's hot, then it's 12:1. I'm running 20* advance at 700 RPMs, 22* 1000 RPMs, holds strong vacuum, purrrrrrrs.

Stock NGK plugs with the gap set to .041".  NGK plug wires.  It is not a secondary ignition problem since it does not exhibit the typical symptoms of such an issue.

Even the wiring for the CYP sensor is shielded as it would be on a stock harness.

I don't care to run a slightly rich idle because on a stock engine, I don't like melted catalytic converters, and it is a band aid fix IMO.

Jesus guys.  You act as if I am spending several hundred dollars on this little project.  It isn't like I am buying an FJO or AEM injector driver.

[patsmx5]

What advance are you running at idle? Just saying if it's a spec too lean from injector latency, just pull a couple degrees of timing out in the problem cells, dial in a spec more idle, done. Especially if you're running a kinda advanced idle already.

[Joseph Davis]

Jesus guys.  You act as if I am spending several hundred dollars on this little project.  It isn't like I am buying an FJO or AEM injector driver.

No, I am acting as if there is something wrong with not being able to get 450cc injectors to idle like stock.  Almost as if there's something wrong with your car, possibly on a basic level that could cause your engine to shitcan itself when boost gets applied.

[snm95ls]

Jesus guys.  You act as if I am spending several hundred dollars on this little project.  It isn't like I am buying an FJO or AEM injector driver.

No, I am acting as if there is something wrong with not being able to get 450cc injectors to idle like stock.  Almost as if there's something wrong with your car, possibly on a basic level that could cause your engine to shitcan itself when boost gets applied.

Ok.

Probably so.

I will investigate further when time allows.

[lilpooh21186]

Jesus guys.  You act as if I am spending several hundred dollars on this little project.  It isn't like I am buying an FJO or AEM injector driver.

No, I am acting as if there is something wrong with not being able to get 450cc injectors to idle like stock.  Almost as if there's something wrong with your car, possibly on a basic level that could cause your engine to shitcan itself when boost gets applied.

true these injectors should idle mint try playing with your other tables like the iat or mabey ect idle offset i dunno the gap also seems kinda big to me for a turbo set up.

[snm95ls]

Jesus guys.  You act as if I am spending several hundred dollars on this little project.  It isn't like I am buying an FJO or AEM injector driver.

No, I am acting as if there is something wrong with not being able to get 450cc injectors to idle like stock.  Almost as if there's something wrong with your car, possibly on a basic level that could cause your engine to shitcan itself when boost gets applied.

true these injectors should idle mint try playing with your other tables like the iat or mabey ect idle offset i dunno the gap also seems kinda big to me for a turbo set up.

There is no turbo yet, and the only issue is at idle.  Factory recommended spark plug gap is 0.039"-0.043"


Pulled the current BIN off my ECU, and the pulse widths are somewhat large even compared to a stock map running stock injectors.  Looked at my old map with the stock sized injectors and the pulse widths are large as well when compared to a stock map with stock injectors.  Apparently there is some issue with the fuel side.

Oh well.  Guess I will have to check fuel pressure, yet again, and then maybe try  a high current(relatively) voltage drop across each injector circuit.

Maybe the resistor box I have is FUBARed somehow.

[patsmx5]

Jesus guys.  You act as if I am spending several hundred dollars on this little project.  It isn't like I am buying an FJO or AEM injector driver.

No, I am acting as if there is something wrong with not being able to get 450cc injectors to idle like stock.  Almost as if there's something wrong with your car, possibly on a basic level that could cause your engine to shitcan itself when boost gets applied.

true these injectors should idle mint try playing with your other tables like the iat or mabey ect idle offset i dunno the gap also seems kinda big to me for a turbo set up.

There is no turbo yet, and the only issue is at idle.  Factory recommended spark plug gap is 0.039"-0.043"


Pulled the current BIN off my ECU, and the pulse widths are somewhat large even compared to a stock map running stock injectors.  Looked at my old map with the stock sized injectors and the pulse widths are large as well when compared to a stock map with stock injectors.  Apparently there is some issue with the fuel side.

Oh well.  Guess I will have to check fuel pressure, yet again, and then maybe try  a high current(relatively) voltage drop across each injector circuit.

Maybe the resistor box I have is FUBARed somehow.

what ohm do your injectors measure and what ohm are the resistors you're running? IE-what's the total resistance the ecu is seeing.

FWIW, I'm running low ohm RC 550s, with resistors wired in, running 62 PSI base fuel pressure( never changes, returnless system), and they idle fine. I can (and have) idle 15:1, no problems, but I choose to run richer for other reasons.

[snm95ls]

Jesus guys.  You act as if I am spending several hundred dollars on this little project.  It isn't like I am buying an FJO or AEM injector driver.

No, I am acting as if there is something wrong with not being able to get 450cc injectors to idle like stock.  Almost as if there's something wrong with your car, possibly on a basic level that could cause your engine to shitcan itself when boost gets applied.

true these injectors should idle mint try playing with your other tables like the iat or mabey ect idle offset i dunno the gap also seems kinda big to me for a turbo set up.

There is no turbo yet, and the only issue is at idle.  Factory recommended spark plug gap is 0.039"-0.043"


Pulled the current BIN off my ECU, and the pulse widths are somewhat large even compared to a stock map running stock injectors.  Looked at my old map with the stock sized injectors and the pulse widths are large as well when compared to a stock map with stock injectors.  Apparently there is some issue with the fuel side.

Oh well.  Guess I will have to check fuel pressure, yet again, and then maybe try  a high current(relatively) voltage drop across each injector circuit.

Maybe the resistor box I have is FUBARed somehow.

what ohm do your injectors measure and what ohm are the resistors you're running? IE-what's the total resistance the ecu is seeing.

FWIW, I'm running low ohm RC 550s, with resistors wired in, running 62 PSI base fuel pressure( never changes, returnless system), and they idle fine. I can (and have) idle 15:1, no problems, but I choose to run richer for other reasons.

Dunno.  I need to check out the resister box.  The resistance of the injectors measured out to be about 3.3-3.4 Ohms when they were serviced. 

[Joseph Davis]

Exhaust leaks, causing the wideband to read lean and therefore the tune to go rich?

Let the car idle for a couple minuts, pull plugs and look at them.

[snm95ls]

Exhaust leaks, causing the wideband to read lean and therefore the tune to go rich?

Let the car idle for a couple minuts, pull plugs and look at them.

It would have to be a pinhole exhaust leak at just the right location.  I run a very quiet exhaust system, and a leak large enough to affect the whole map would be pretty significant, therefore audibly noticeable I would think.

I will try it later when I need a break from working on homework.

[snm95ls]

Resister box measures 6.1 - 6.3 Ohms.

13.3 Volts at measured between the input B+ at the resister box and grounded at the intake manifold.

14.4 Volts between the terminals on the battery.

I can get rid of the lean missfire by upping the idle speed quite a bit.  Tach normally reads ~ 650 RPM, datalogger usually reads about 720-770 RPM at idle.

I tried a quick ghetto tach by using the frequency input of the DVOM I was using.  I was getting a reading of 240 Hz. which should be about 460 RPM.  Dunno how accurate that method is or the meter in that mode, but I know damn well it does not idle at 460 PM.  lol.

I opened up the idle air bypass screw until it smoothed out, besides the slight surge, and it was about 950 RPM according to the tach.  I don't care to idle at that speed on a stock camshaft as there is absolutely no point.

Didn't pull the plugs either.  I will try to do so tomorrow, but I can't imagine an exhaust leak causing it to run rich and giving a lean missfire.  It just doesn't add up.

[patsmx5]

What timing does the engine idle at?

[Joseph Davis]

90% of Honda engines idle at 16 degrees, the later D-series were 12 and some F/H ran 17/18.

[snm95ls]

What timing does the engine idle at?

16.5 on the map.

Middle mark on the damper according to the timing light.

I really do not think a stock cam with unaltered camshaft timing would exhibit such behavior(the lean missfire) only after changing injectors.  If alterations to the ignition timing is needed, then it is a band aid.

[d112crzy]

Oil contamination perhaps? I've noticed, on higher compression engines, that if the valve seals are fucked or just burns some oil, the car doesn't like to idle at anything over 13.5:1(varies from car to car, of course). And this is on stock injectors.

My 450's idle like a champ at 14.5 @ 850rpm on my H22. Stock resistor box(accord).

[snm95ls]

Oil contamination perhaps? I've noticed, on higher compression engines, that if the valve seals are fucked or just burns some oil, the car doesn't like to idle at anything over 13.5:1(varies from car to car, of course). And this is on stock injectors.

My 450's idle like a champ at 14.5 @ 850rpm on my H22. Stock resistor box(accord).

This engine is pretty damn healthy, and I doubt thee is any abnormal amount of oil entering the combustion chamber.  I will pull the plugs when I get a chance and post pictures.


On stock injectors, this little issue did not exist.

[Teg2boo]

My 450's idle like a champ at 14.5 @ 850rpm on my H22. Stock resistor box(accord).

Same thing here, no issue at all. I use the resistor box from my deceased 91 teg.

[toyolla86]

i plugged my dsm 450's in (plug-n-play)
and they've been great for me so far.
rich if anything.

[DmC]

your whole problem is probably just battery offsets and iat ect compensation.