replacing injectors

[lithiumus]

I suspect that the root of some of my idling, emissions issues could be rooted at the injectors. After replacing my cats, o2 sensors, vacuum hoses, PVC, etc, I still fail idle emissions and have seesaw idle most of the time around the 600 - 1100 rpm. If I tap the fuel a bit, I can usually stabilize it.

Can I replace my injectors with larger ones from RC Eng? I am planning on future engine upgrades and figure why not buy larger ones now. Will this work? will I need an EMS to tune them? or will the stock ECU adjust the larger injectors properly?

 

[LJSB]

It is more likely the problem you have is from a dirty throttle body. It is the least expensive fix (cost of 1 can of throttle body cleaner) and a easy DYI.
I doubt the problem described is the fuel injectors.

You would be better off getting the correct size injector for the particular needs and demands of the modification you are doing at the time of execution.
For now, I suggest getting the car to run correctly before modifying the fuel delivery system. Just my 2 cents.

 

[lithiumus]

Thanks for the reply. I actually cleaned the throttle body already. I cleaned it myself, then brought it to Acura where they did another cleaning when they removed the idle screw and adjusted the idle.

I suspect that it's only 1 injector that might be causing this or potentially a spark plug. When the weather is colder, you can see the uneven smoke from the tailpipes which leads me to believe that it's isolated to one side of the engine i.e. one bank of plugs or injectors.

I figure the OEM injectors will cost me more than aftermarket so why not just get a set of larger aftermarket injectors. If that doesn't work, I guess I'll stick to the OEM and see if I can get a discount somewhere...

 

[Bryan]

Why get larger injectors? This is just more likely to confuse the ECU. Yes, it will run closed loop at idle and correct for larger injectors, but you'll be further away from the initial settings and probably get less accurate fuel metering. I suspect you will just go overrich when the ECU goes into open loop.

You'd be better off to send your stock injectors to RC Engineering to get them cleaned and flowed. You'll know whether you had a problem to start with and you'll get back matched injectors with the proper flow rate. Search the forums for RC Engineering and you should find an example or two.

Scratch all the above advice if you plan big mods and custom engine management. If so, go for it and post the results!

 

[Briank]

Replacing the injectors is unlikely to help your idle problems and is more then likely is it will just make more problems. I believe you just have a simple idle control problem. The ECU controls the idle speed with the EACV (electronic air control valve). For the ECU and the valve to work properly the fast idle valve, the throttle plate, the air bypass adjustment must be set and working correctly. Also there should be no vacuum leaks.

If your throttle body is clean and no one has messed with the stop screw that should be fine but it's hard to know who or what has been messed with.

I would start by setting the air bypass following the procedure in the service manual. I would ASSUME dealer adjusted the air bypass correctly but you are still having idle problems so you may have to re do it.

Also any vacuum leaks will cause problems go over every thing again. You can spray down the connections with carb cleaner with the engine running and if you hit a leak you will here the engine speed change.

 

[lithiumus]

Thanks Brian,

That makes a lot of sense and I'd rather not spend money if I don't have to, god knows I've spent too much already...

I'll readjust the idle and actually get a new idle screw as it looks like it's almost stripped... obviously there has been tampering at some point... the Acura dealer mentioned this as well.

I'll do a spray down of the connections. Should I replace all the vacuum hoses proactively, just in case the carb cleaner doesn't catch it? Doesn't cost a lot anyway...

 

[Briank]

Thanks Brian,

I'll do a spray down of the connections. Should I replace all the vacuum hoses proactively, just in case the carb cleaner doesn't catch it? Doesn't cost a lot anyway...

Just fix/replace what you find bad. The more you do the better chance you have of introducing new problems.

 

[NSXTech]

If tapping the throttle clears up the problem, you do not have an injector issue, IMO. What the info we need to help is, is what your emmissions failure was. CO, HC, NOX, and at what numbers. It is highly unlikely with new cats and O2's, that you are running rich. If an injector was leaking enough to cause the failure, the car would probabally run poorly. If one is plugged, the idle would not hunt, but you would feel the misfire at idle.

What are your emmissins results?

MB
ps, Do NOT oversize your injectors.

 

[lithiumus]

My 40km or driving emissions passed with flying colors... but my idle HC are 740 and 860 ppm for the 2 smogs I did. Co2 is 0.09 so it's fine at idle.

The hunting somtimes stops when I tap the gas at idle, but not always. During the hunting, when it dips, the car almost stalls. At night the lights dim during the dips and brightens up during the surges.

Does this happen when the idle is off? or maybe it could be the EACV malfunctioning and causing it to dump fuel at idle...

 

[Briank]

My 40km or driving emissions passed with flying colors... but my idle HC are 740 and 860 ppm for the 2 smogs I did. Co2 is 0.09 so it's fine at idle.

The hunting somtimes stops when I tap the gas at idle, but not always. During the hunting, when it dips, the car almost stalls. At night the lights dim during the dips and brightens up during the surges.

Lights dimming when the idle is real low is normal.

Does this happen when the idle is off? or maybe it could be the EACV malfunctioning and causing it to dump fuel at idle...

The EACV controls the air flow if the idle bypass is not set correctly the EACV will not be able to properly control the idle speed. Have you checked the setting of the idle bypass using procedure the service manual?

 

[zahntech]

860 hydrocarbons is alot, like a whole lot, most well worn honda/acuras that run decently run at about 10-20 HC at idle, your new cat converters are not going to like that at all!! how long has this been going on and has any other work been done to the car lately?..JZ

 

[zahntech]

This may sound like a dumb question but how is your cooling system? is it full? have you checked the Coolent temp sensor? if the coolent isnt full the idle will hunt and the computer wont know how warm the motor is..also if the sensor is reading cold when the car is hot the car will run very rich and not necesseraly set a fault code. just a possibility...JZ

 

[nsxexotic]

one time I had a problem with the Idle air control valve making the tach jump at idle... bleed the coolant and everything fine on my accord

 

[lithiumus]

My coolant was changed at Autowave about 6 months ago and I've driven very little since then. The coolant level is looks good.

I talked to Autowave about this as well and they indicated that either it was a faulty O2 sensor or that one of my injectors was leaking as Shane also agreed that 860 HC is a ton of emissions.

With the advice of some of the Prime members, I tested the temp sensor that the ECU reads to determine whether the car has warmed up. Aparantely, the car runs rich during warm up but I connected a multi-meter to the sensor connector (pain the butt) and watched the resistance change as the car warmed up and it's within spec according to the Service manual.

The reason I suspect a faulty injector is that it may be that one injector is not closing properly and dumping fuel. When I'm driving, the issue goes away since the injector opens up anyway. The extra rich fuel mixture during idle may be why it hunts...

i.e. the ECU senses that it's too rich, so it adjusts and allows more air in, it quickly leans so the ECU reduces the air but the faulty injector continues to dump fuel so the ECU adjusts again...

Does that make sense?

 

[Briank]

I guess you really want to change the injectors. Unless you have a miss at idle its unlikely you have a bad injector.

I did find this in the parts for sale.

http://www.nsxprime.com/forums/showthread.php?t=54481

 

[zahntech]

I would not be too concerned about the o2 sensors as the o2 sensors do not provide much if any mixture adjustment below 2000 rpm, If you are leaking fuel thru the injector(s) you can attach a fuel pressure gauge and watch the fuel pressue drop after you shut the car off, finding 860HC of extra fuel should not be that difficult to find, also if you have a bad coil or 2 you will be pumping raw fuel out the tail paipe witch is what hydrocarbons are ...raw unburnt fuel....while its idling you can unplug each coil one at a time and if you do not notice a differance in how it runs than you know that cyl is where your problem is...good luck..JZ

 

[lithiumus]

I might just get the injectors and swap them out just to know that they are "known good". If my OEM injectors are good, I'll probably send them off to RC as well and sell them.

JZ, do you mean unplug an injector from the resistor coil or do you mean unplug a spark plug from the coil? Will this hurt the engine in any way?

Someone also suggested that I may have a bad or dirty spark plug that my not be burning all the fuel cleanly... 860HC sounds to me like fuel is literally being poured into the engine at idle...

 

[zahntech]

If one or more of your coil/spark plugs are not providing you with ignition you will have a rough idle and the engine will "miss" if you remove the covers over the coils and unplug them one at a time and note how it effects the idle you may find that one or possibly 2 cyls are not doing thier share IE if you inplug the #4 coil and it has no effect on the way the motor runs, than that cyl is not firing properly, you will most likely set some codes in the computer while doing this, you will need to clear the memory afterwords, if you find that a cyl is not doing its part than you need to findout why? is it a bad coil? bad plug? leaking injector flooding that cyl?, if you swap a coil to another cyl and the problem moves with it than you know you have an issue with that coil...Good luck...JZ

 

[lithiumus]

Yes, I know it's almost a year later... but I didn't work on the car during the off season...

Though I haven't retested smog, I'm pretty confident that issue is dealt with. I sent my injectors to RC Engineering to get serviced. When I got them back, the report showed one injector that had a "dripping" pattern.

After I reinstalled the injectors, I could tell that the exhaust fumes after the car was warmed up were a lot less rich and had a slighly sweet smell compared to rich fuel fumes.

It didn't fix the fluctuating idle but I'm narrowing it down... it's definitely not a vacuum leak. when I reinstalled the injectors I forgot the fuel regulator regulator vacuum hose and the idle fluctuated very smoothly and in an almost controlled fashion.

My idle was stable after I fixed the vacuum leak... but when I tap the throttle and blip the RPM, that's then the fluctuations occur. The pattern is almost as if when the RPM is dropping back and would normall stabilize, it can't and drops under, then the car blips the RPM. It's very erratic, unlike the a vacuum leak.

I'm suspecting EACV or one of the other idle controls that Brian has indicated. I'm going to play with it some more tomorrow...

 

[Thom]

Faulty coil-packs could be added to your list. I had a problem with this when getting my emissions done during winter months, Texas. During the heat of the summer it passed. The coil-pack resistance changed just enough over temp to cause poor firing. Take it for what it's worth.