Misfire

[TheSebringOne]

Just picked up car from HUK where I had oil & coolant service, they stated theres a engine misfire & needs investigation! Service manager said he wasn't sure their dignostics had the software for the NSX, then the lad that did the test said they do!? He suggested since I don't drive the car alot, I should try their injector cleaner as they use it all the time and he stated it works a treat? They use Havoline? Any ideas guys please.

Cheers :)

[Kevin]

I'd just use it more. Give it a good 200 mile run and see what it's like.

[nigel]

Make sure your rear bank of plug coils and plugs are dry and free from corrosion.
When you wash your car they can fill with water and cause a mis-fire. This happens alot here in the states.
If that's not it, save the money from having the dealer do the work and get a large can of "Throttle Body Cleaner" from the auto parts store. Disconnect the intake duct from the air box to the throttle body and spray it thoroughly. You'll see if it's dirty when you disconnect the duct.
It's a good idea to use "Techron", Chevron brand fuel additive "Injector Cleaner" every now and them to be sure the intake tract stays clean.
Just some thoughts.

Cheers
nigel

[TheSebringOne]

I will give it a go after the Festive period, but where can I get Chevron Havoline Techron? Looked everywhere on the www, Halfords, Ebay, Amazon, Motorworld etc & but only get it in the States, seems no one sells it in the UK!? If thats what Honda is selling, then they must exclusive rights as they used Havoline engine oil? Its about 15 squid a tank treatment bottle.

This Techron is a pure concentrated version of the stuff that goes into petrol to clean your injectors/engine and has been highly rated on alot of forums.

[Kaz-kzukNA1]

Hi.

It would be interesting to know whether the misfire was already there or not before leaving the car at the garage for oil/coolant services.
Also, is it misfiring for all rpm range or under a certain condition only?

It may be difficult to tell on above points as it seems that you don’t take out NSX frequently.

If the garage has the diagnosis tester, they should be able to get further information from DTC (Diagnostic Trouble Code) which is more detailed than counting the number of Engine Check Light (if you have any failure, of course).


If it is due to the poor spark, then it could be related to the spark plug and IGN coils which can be checked quite easily. As nigel mentioned, the water could find its way into the Rear bank IGN coil area so it is a good idea to replace the rubber sealing attached to the rear IGN coil cover regularly. I replace it every 2 years with silicone grease applied and so far, all of my original IGN coils survived for 14 years without any rust on the metal plate at the coil head.

If it is due to the poor compression, then you can carry out the compression test and also the leak down test. However, if you didn’t notice any misfire before, then this is very unlikely to be the cause as any mechanical failures in this area won’t fix by themselves.

If it is due to the poor mixture, then it could be bad/old fuel inside the tank but then, you would notice it before leaving the car at the garage unless they re-fueled the car for you (how old is your fuel?). It could be sucking extra air from somewhere around the throttle body or at the header/exhaust causing wrong feedback data from O2 sensors. Or, the ECU is using too rich/lean co-efficient value due to the failure of O2 sensor itself and so on.


If you don’t get Engine Check Light and none of the above test/check nor the garage managed to fix the misfire, then you may want to consider the following.

Based on your signature text, your car seems to be 99 3.2L MT model.
This means that your car is controlled by DBW which no longer uses the EACV (Electronic Air Control Valve) that tends to cause unstable rpm (or if we call this misfire) at idling.
Because of this, as nigel stated, it was quite common to clean the throttle butterfly area including around the EACV port on the pre Mar/95 model.
On DBW model, ECU is controlling the throttle butterfly directly to the target rpm value even for the idling so it is still important to keep the butterfly very clean.
I clean it at least once or twice a year but it depends on your driving condition. You can use the one from leading manufactures stating as Carbulator/Injector cleaner/conditioner.

From Sep/99 model, all of NSX was equipped with Secondary O2 sensor on each bank. There will be 4 of O2 sensors (1 x Primary, 1x Secondary for each bank) on the car.

Whenever I encountered with misfire or unstable rpm issues, I’ll first reset the ECU by removing the ‘clock’ fuse to clear the study co-efficient value stored inside ECU memory. Then, disconnect the Primary O2 sensor connector (I only have the information on your car as 99 model so I don’t know whether you have 4 or 2 of O2 sensors). Next, start the engine and go out for a short ride but try to go through all rpm range. You will get Engine Check Light as you have disconnected the Primary O2 sensors but in this way, ECU is in Open loop control and just uses the default co-efficient value for the part of the FI calculation. Thus, it eliminates the certain O2 sensor failure mode causing wrong mixture which can’t be detected by the ECU algorithm.
If it fixes the misfire, then it is O2 sensor related. If not, then at least you know that the O2 sensors are fine and start another investigation in other areas.

I think it is getting too long and possibly went too far so I'll stop now....


Regards,
Kaz

[nigel]

How can I add to Kaz's response?
Kaz, Your The Man. I felt good with "clean the t/b and check for H2O in the rear bank.
I hope I will get to come over soon and spend some time with you.
My new job with American Eurocopter may afford the opportunity in the very near future. Be on the lookout.
As for the Techron cleaner, Chevron is a world wide corporation and they should have a distributor in the U.K.
"Larry B" on Prime raves about it and that's why I started using it. He, like Kaz, when they speak, stop, listen, (or read) and learn from what they say. It's the business.
I noticed a marked cleanliness in my intake tract, (t/b and injectors) after using it and never a mis-fire
Back to the cleaner. If you can''t find it let me know and i'll start a look see and get you some retailers.

Cheers
nigel

[TheSebringOne]

Latest update, tried 3 things:

Put HUK's recommended injector cleaner with a full tank of V-Power and so far travelled 2 runs totalling 40 miles. Any improvements, not sure and need a very long run maybe. Maybe when the full tank used I will know?

Checked the 3 back bank coils plates, theres no corrosion. Also the contact point inside the coil tube are fine too. Not checked the plugs, how far down are these and what socket size do I need? Plugs only done 6k miles in 3.5 yrs. Is the rubber sealing the one that fits on the edges of the plastic dark grey cover, my only had one, so when I put it back together, I left this on top for now & I must get another for the lower edge?

Checked TB, the inside tube was clean, couldn't push the butterfly valve open, so started ignition & sprayed cleaner which stalled it. Without restarting & leaving key in stalled position, pushed valve opened & sprayed in alot of cleaner. Started up, but nothing, restarted again & gave some gas, which engine slowly fired up. Engine sounds ok, so going for run tomorrow.

Must take out & put back in clock fuse too before I go out too.

[TheQuietOne]

Plugs only done 6k miles in 3.5 yrs.

I think this is your problem....what is the point in having the car?? You could just get a full size model made for a couple of grand and save the depreciation...:D

P.S. I have done 50,000 miles in 3.5 yrs in mine and no miss-fires - or indeed any problems at all!

[Papalazarou]

I think that kzukNA1 post pretty much covers it.

A couple of points though; HUK doesn't endorse any specific brand of fuel additive; I know this because I am a distributor for the largest additive company in the UK and have spoken to Honda about this. It's more likely that the dealer sells a product and infers that it is recommended by the manufacturer.

If you are going to use an injector cleaner ty to get hold of a 'good' workshop only brand. They are stronger and more thoroughly tested. Obviously I'm biased but I recommend you try Wynn's 'Injection Power 3' (or forte if you have to - we compete). IMO Wynn's is about as good as injector cleaners get. It's highly researched and will also inprove the quality of the fuel it mixes with.

The Havoline product quoted is a cheaper lower grade product made by fuel/oil companies dabbling in the speciality chemical market.

Secondly, as stated a Carb/air-intake cleaner is a good idea. Just make sure you select a product that doesn't remove the protective coating on the inside of the throttle body.

Cheers,


James.

[markc]

Just picked up car from HUK where I had oil & coolant service, they stated theres a engine misfire & needs investigation! Service manager said he wasn't sure their dignostics had the software for the NSX, then the lad that did the test said they do!? He suggested since I don't drive the car alot, I should try their injector cleaner as they use it all the time and he stated it works a treat? They use Havoline? Any ideas guys please.

Cheers :)

Hi Sebring, you haven't actually said whether you have experienced the misfire or can feel it misfiring now?

Could it be there was a misfire which the ECU recorded and garage picked up with their diagnostic equipment but which has now gone away? Codes are 71 thru 76... http://www.nsxprime.com/wiki/Trouble_Codes

Intermitant problems like this do occur when you don't use a car very often. Do what Kevin said, take it out for a good thrash to kill or cure any intermitant or hibernation related issues.

I'll check my mileage between the last 2 MOT's I think it's less than 1000miles... shame on me!

Cheers

Mark

[TheQuietOne]

I'll check my mileage between the last 2 MOT's I think it's less than 1000miles... shame on me!
I think I'm going to have a 'Thread Of Shame' made a sticky somewhere on here for you owners who don't seem to know where the key goes in your ignitions.:rolleyes:

[TheSebringOne]

TBH I'm not sure if theres a constant misfire, before I took it for a service, I drove the car very little & through the Winter I just let the car charge up stationery. With HUK's Havoline performance plus & V-Power it idles ok after start up, seems to pull through each gear and when I go out, I go for a blast down my favourite roads. I will do the clock fuse thing & go for a long journey soon. Thought I was a low user! Face the TQO wrath! :D

TQO, whats the point of fake model which is all show & no go! I could put her in a glass case tho! :laugh: SPLAT

James I have been trying to get Chevron " Techron" but no joy in the UK, Euro, seems only you can get it in the States. Havoline have started a treatment programme through certain dealers, HUK being one to use their product.
http://www.havoline.com/uk/the_solution.html
http://www.havoline.com/uk/index.html
http://www.havoline.com/uk/the_programme.html

[Papalazarou]

James I have been trying to get Chevron " Techron" but no joy in the UK, Euro, seems only you can get it in the States. Havoline have started a treatment programme through certain dealers, HUK being one to use their product.
http://www.havoline.com/uk/the_solution.html
http://www.havoline.com/uk/index.html
http://www.havoline.com/uk/the_programme.html


James,

I'm still not convinced it's a HUK thing. If it is they should be ashamed of themselves as it's at the lower end of the quality scale. there's probably nothing inherently wrong with it, but why use that when you can use a premium product.
Cheers,

James.

[TheSebringOne]

Maybe its not exclusive to HUK, but any dealers that choose to sign up to their products? Anyway I may give Wyns a try when I do my next treatment since if anyone knows their products, it would be you James.

Cheers