'97 Q45, stumbling idle through 2000 rpm m.o.l.

[kimsracer]

All right then, I have owned this Q for about two months and have been searching this forum for solutions to the problem I am having. To summarize, some background first. It is a 1997 Q45 with 122,xxx miles, It began to have an intermittant " stumble" or "misfire" at idle which would occur suddenly and last for less than a second. This would happen independent of the position of the transmission lever, and of the load on the engine such as running the a.c. However, if the car is in a drive gear, or there is a load on the engine the "miss" would become more freqeuent and more pronounced.I began treating this problem with the common solutions...Cleaned ,1. then replaced the MAF, Seafoam ( intake through the brake vacuum line and the vacumm port at the front of the intake as well as the fuel tank), 2.fuel filter replaced, 3.changed fuel, 4.replaced the spark plugs( correct Denso) oil and filter change (verified level)5. Transmission fluid change. 6. Cleaned the intake as well as possible 7. checked the vacumm hoses for leaks. 8. checked the intake for leaks. As well as numerous hours looking for anything out of the ordinary. The fuel pump does not hum or buzz.I do not have a check engine light.The only relief I have had is the few miles after I Seafoam the intake, after which the problem reappears as bad as before.

If I had the equip. to check the condition of the spark or for misfires I would but hope that it does not come down to paying for professional services unless it needs it.

[3Q Jay]

0. welcome.

4. denso? you mean NGK? most here won't use anything but the pfr5g's, a few like me have the ifr-5e11's.

8. there was a tsb for intake gasket (upper one) leaks--has yours been fixed?

coil pax o-ccasionally fail on the fy33, seems especially after servicing plugs.

[maxnix]

It is a 1997 Q45 with 122,xxx miles, It began to have an intermittant " stumble" or "misfire" at idle which would occur suddenly and last for less than a second. This would happen independent of the position of the transmission lever, and of the load on the engine such as running the a.c. However, if the car is in a drive gear, or there is a load on the engine the "miss" would become more freqeuent and more pronounced.

1. then replaced the MAF, Seafoam ( intake through the brake vacuum line and the vacumm port at the front of the intake as well as the fuel tank),

4.replaced the spark plugs( correct Denso)

1. Seafoam is NOT recommended by any tech on this board due to its alkalinity.

4. Correct plugs are NGK Laser Platinum as specified in all FSM and OM.

Have you cleaned the EGR valve and hose? IAC valve?

I think you are only a step away from solving your problem.

Keep us posted please.

This post may end up in Infniti Online Mechanic where operational information is posted.
Modified by maxnix at 10:34 PM 6/7/2006

[FarFetched]

I think you are only a step away from solving your problem.

That staep is not a pleasant one - KS and harness is in your future! I am good psychic or what ?P.S exstensive BG44K therapy and possible fuel system flush!

[Solini]

All right then, I have owned this Q for about two months and have been searching this forum for solutions to the problem I am having. To summarize, some background first. It is a 1997 Q45 with 122,xxx miles, It began to have an intermittant " stumble" or "misfire" at idle which would occur suddenly and last for less than a second. This would happen independent of the position of the transmission lever, and of the load on the engine such as running the a.c. However, if the car is in a drive gear, or there is a load on the engine the "miss" would become more freqeuent and more pronounced.

After I had my spark plugs changed on my Q back in Feb. two of the coils went array. Try going to the dealership and have them plug in a OBD scan tool and see what it says. Good luck

[miata007]

You description of the idling problem matches exactly of what I am having on my 97 Q45t with 137k. I haven't resolve the problem yet. Here's what I did regarding to the KS and harness.

Last year, my car was attacked by mice building a nest in the engine and chewed off the KS cable. As a result, I took the effort to replace the cable and at the same time replaced both KS sensors (NEW). After that I was hoping my situation improves regarding to the idling. Turns out it didn't make a difference. Atleast I didn't feel it.

My MAF is replace two years ago so I don't want to go that route. I am planning to replace the fuel filter but from your post, seems like it is not the problem. I am beginning to think it is either the fuel injectors or the coils that is causing the stumbling/misfire. Both are equally expsensive so I am afraid to try unless able to confirm. I am really in the same situation as you right now.

From this forum, I read there is a way to measure the resistance of the fuel injectors. I haven't got to it yet. Please let me know if there is a way to findout which specific coil is failing.

007

[miata007]

I have a question for you.

For my car, when I used Chevron Super unleaded, keep my fuel tank full, and use a bottle of Techron fuel cleaner, the problem seems to improve dramatically.

Can you try that and see if it helps? If it is the case I am thinking about the problem could be related to fuel (ex dirty gas tank).

007

[Solini]

I have a question for you.

For my car, when I used Chevron Super unleaded, keep my fuel tank full, and use a bottle of Techron fuel cleaner, the problem seems to improve dramatically.

Can you try that and see if it helps? If it is the case I am thinking about the problem could be related to fuel (ex dirty gas tank).

007

I'll steal one of maxnix normal responses and say check a recent post by q45tech, he mentions something to the effect of buying "bad gasoline" that ruined a lot of cars

[maxnix]

I'll steal one of maxnix normal responses and say check a recent post by q45tech, he mentions something to the effect of buying "bad gasoline" that ruined a lot of cars

A good cheap idea is to run some ISO-HEET (not HEET) through it to dissolve any water in the tank. Try a couple of bottles.

[paranoidjack]

I HAVE THE SAME PROBLEM. 82k '00.

It is so annoying to have people ride in this beautiful car and listen to it choking at it's otherwise silent idle. I will be watching this thread closely, and trying the water remover from my tank.

I have also noticed that with some gasoline the problem seems to disappear for the full tank...perhaps it's not that there's a PROBLEM with the coils packs, just that with age the car's ability to correctly use diff grades of gasoline is compromised.

[kimsracer]

O.K.I pulled the EGR valve and IAC and cleaned both with brake cleaner. The IAC had some carbon deposits and grit on the plunger. The EGR valve was dirty , but not exceptionally so. Long story short, problem seems to have been eliminated. The stumble is gone, and the engine accelerates smoothly all the way to redline. Thanks for the help, I will update later.

[maxnix]

Thanks for reporting back. I hope you do update us with in a few thousand miles.

[miata007]

No kidding! How did you clean the EGC valve? What is an IAC? I tried searching that on the FSM but can't find it. I must give it a try this weekend.

When you get a chance please post more details so I can make an attempt this Sunday. I really hope this is the end of our Y33 problems.

007

[kimsracer]

HAH HAH HAH!!!!The Infinity gods have sucker punched me again. The problem is back, but does not seem to be as bad. what is next? I have tried different brands of fuel, I have tried the iso-heet. After driving this evening I noticed it is almost non-existent when the car is in park and the ac off, but comes back when I put the car in a drive gear. Possibly a transmission problem? It does not seem to be but I am open to any suggestions.zeropost?cmd=reply&id=1851418#http://fo ... er...51418#

[kimsracer]

The IAC is refered to as the AAC in the Infinity literature I have seen. As far as cleaning the EGR valve. First, remove the pipe from the exhaust system, then remove the two bolts that connect the valve to the manifold adapter. pull the rubber hose from under the other disk on the passenger side, now you can pull the valve out of the engine bay. Liberal amounts of brake cleaner inside and out the replace. That is pretty much all I did.

[slinger5150]

Just bought a 99' Q45t a week ago. It has 90,000 miles on it. I have noticed its doing the same thing. I will be watching to see if anyone comes up with anything. I got a 3yr/36,000 bumper to bumper with it. I'm going to collect al the little issues for about a month and bring it in to have them fixed. Its a $100/ each drop off at the dealer. It doesn't matter if I have 1 or 10 issues.Chris

[miata007]

Damn it! I know it is not going to be that easy. Atleast, I am excited for the past couple of days.

Anyway, I am going to give it a try this Sunday regarding to cleaning the EGR and AAF valves. Also, I am glad that there are 4 of us who is working on the same problem. I have tried to post this problem here before but no one step up with the same car/problem. Most folks here are familiar with G50.

I will give you guys an update to see if the problem goes away.In the mean time, lets keep working.

007

[miata007]

kimI doubt it is a transmission problem if your car is in drive but you are at a stop. Still, I am thinking it is a fail fuel injector or coil. Can you find the time to figure out how to measure the resistance of the fuel injectors?I am relying on you.

007

[ddrumman]

A good cheap idea is to run some ISO-HEET (not HEET) through it to dissolve any water in the tank. Try a couple of bottles.

How would you use it? Just add a bottle to the tank like with BG44K or....?I'm thinking of using some of it on the MG.

[maxnix]

Maybe examine the plunger operation in the IAC valve for smooth friction free operation?

OBD II ananlysis or pull the plugs next?

[blind6]

I have a stumble with my Q also, but it only occurs when I'm idling and not moving. It did it for a while till the CEL came on. Had it scanned and got the code P0420, Catalyst system efficiency below threshold Bank 1. After a couple days the CEL cleared itself but the problem still remains. It is very inconsistent and does not effect the idle when it stumbles.

I am shipping the car this week from Hawaii to Missouri and I have no time or tools to troubleshoot. Has anyone encountered this problem?

We had gone to the beach and when my wife pulled in there was a slight drop-off from the pavement and the front dropped and it scraped. When I look at the exhaust pipe there is a scrape under the left rear O2 sensor. Could that scrape have knocked something outta whack? Sorry if this is way off track but a stumble is a stumble and someone else may have experienced this.

[paranoidjack]

we're all working together on this one. I've put in 3 calls to local infiniti techs but no one seems to have seem it...that seems fairly ridiculous since 4 or 5 of us have it, it must be fairly common.

Q45Tech? Any ideas?

Also, I think it's important that the 5 of us discuss the car's fuel history. I am in agreeance that it is a coil/injection problem, since it only occurs under almost no load.

I bought my car at 74k with unknown history. I pulled a carfax and it seems to have been all over the place, but given the condition of even the leather I am sure the previous owner(s) were good with it. But that doesn't mean they waxed it frequently and put in 87 all the time to pay for the wax, hah!
Modified by paranoidjack at 3:16 PM 6/12/2006

[slinger5150]

I just bought mine recently also. It is in pristine condition. I can only asume the previous owners took good care. Its never been reported in an accident or anything either. I've only put premium in it since I bought it.

Chris

[miata007]

HistoryAfter the purchase (June 2005), I was able to get history from the original dealership. The previous owner reported a lack of power going uphill and required flooring of the gas pedal. The dealership tested the car in multiple occasions but never able to resolve the issue. At one time, they did observed a misfire and suggest to replace 2 KS and 8 coils. The repair cost was expensive and i guess that was the reason why the previous owner decided to sell the car. That was a hard lesson I learned.

Anyway, I replaced the 2 KS on my car myself. The stumbling problem hasn't improved a bit nor does the fuel economy. I wanted to do the coils but is too expensive unless I am able to confirm they are bad.

They previous owner was a cheapskate. She only used unleaded 89 (plus) on the car. If she can't afford it, why does she drive a Q?

What is you guys opinion in replacing all the coils? Should I do it anyway since my car is at 141k? Or should I wait until the right diagnostic is done first?

007

[maxnix]

Wait until they are correctly diagnosed.

The history of running 87 is not good, though. Probably gave the KS lots of exercise.

[Jesda]

Go ahead and use Seafoam. Some have also suggested GM Top End Cleaner because its more specialized.

[Falkdesigns]

I've been following this thread, but don't have much to contribute other than I feel bad for you guys, and it sucks to hear all of this. The only thing I do to mine is change the Amsoil once a year, air filter every 6 months, Chevron prem (91), and fuel system cleaner every 2-3 months. I hope you guys figure out what's causing the issue, I'm curious to see what it is.

[maxnix]

Go ahead and use Seafoam. Some have also suggested GM Top End Cleaner because its more specialized.

SeaFoam considered way too alkaline by Q45tech. TopEnd cleaner and intake foggers won't do much for IAC nor EGR valves as they will never see it.

Wife got tired of stumble, so off came intake for a kerosene cleaning, and same for EGR and IAC valve. Used only carb cleaner on lower runners. Seems to have cured the stumble. Will let you know later. Dremel helps a lot, but inside of penum is really rough cast with lots of nodules on the surface. Cleaned as best I could.

Also, I am running the NGK 5 heat range for TX. I'll post a picture of the runners in IOM and you'lll see how unevenly the EGR tube disperses the gases.

Did trip the CEL with a P1105 code, but got it reset.
Modified by maxnix at 12:49 PM 10/15/2007

[miata007]

A co-worker of mine also owns a repair shop. I mentioned this problem to him and he told me to bring my car in to hook up to OBD2 (diagnostic tool). I told him you must have Consult specifically for Nissan/Inf cars only. Is that true? I am interested in finding out if my coils or fuel injectors are bad. Can a consult/obd2 tool detect that?

007

[96Qowner]

An OBDII reader will do just fine for codes.