98 q45 acceleration stumble?

[reidness]

when she is cold i have no problems with get up and go, but within 2-3 mins of driving and getting up to temp it will stumble when given gas, if you baby it it does pretty good but if you stomp it bogs and stumbles and then goes, it idles fine has 104k on the motor i just did a oil change and pulled the filter and installed a new unit, in augest this car had a complete fuel system flush and new plugs installed the paper work said platinum plugs? not sure what brand,i also just had thew electrical system checked out with a full load and battery,alt are good, but its weird that it doesnt act up cold? im new here and it has been great to read all the info here, thanx in advance

[silkysmoothyjud]

when temp is a factor it is the MAF (clean it) or the injectors. At least thats the case on te 94....

[silkysmoothyjud]

when temp is a factor it is the MAF (clean it) or the injectors. At least thats the case on te 94. Put some ISO-heet in the gas tank...

[reidness]

Thanx for the quick reply, how much iso heat, i have a 1/4 tank now, and im not sure how to clean the maf could you help me out, do you pull the air box off and undo the 2 clamps and then what, or are we unplugging the sensor plug and doing something else? thanx reid

[loystock]

A bottle of Iso-Heet (@ $3) , and a bottle of RedLine SI-1 (@ $7) Fuel System Cleaner (or BG44K - online only @ $18) in a full tank of Premium ONLY top-tier gas (Shell, Chevron, etc.)

I suggest you clean the entire air intake - filter (replace as req'd), MAF sensor and connector and throttle body. This requires removal of the top engine cover.

If you want to clean the MAF sensor and connector only, you have to:- take out the front air intake (disconnect Air Inlet Temp Sensor connector, remove 2 10mm bolts, pull out and disconnect radiator rubber tube)-remove filter cover and air filter.-disconnect 3 hoses connected to the main air intake tube and disconnect MAF sensor connector.- there are 3 adjustable clamps from the MAF sensor all the way to the throttle body. Your choice which one to remove but eventually, you have to remove the one close to MAF sensor.-use zero-residue contact cleaner or CRC MAF Sensor cleaner to clean the MAF sensing element. DO NOT TOUCH IT.-clean the MAF connector and apply dielectric grease (Permatex @ $5)-parts above are available from Autozone and Napa.

Is the CEL on? Autozone provides free scan. This may also uncover 'ghost' codes like Knock Sensor (P0325). Get a printout of fault code, if any.

You might as well clean the EGR valve and hose and the Idle Air Control Valve (IACV).

If the stumbling continues and you car has more than 100K miles, your ignition coils and spark plugs are due for replacement. Refer to the link below for additional info.

http://nico.zeroforum.com/zerothread?id=431321

Fuel delivery may also be an issue (fuel pump/control unit, fuel filter, injectors).

[silkysmoothyjud]

go to q45.org for full details and future reference. No prob, Happy Holidays!

[reidness]

thanx but check this out, on the way to pick up some injector cleaner and maf cleaner the check light came on blinked for a minuit then went solid with a p0301 knock sensor cylinder #1 misfire, i also a week or so ago had P1110 code about the valve timing control left bank, i cleaned out the selenoid and checked out the connector, the wire had a short when bent so i repaired and thought i was good as far as codes and i was focusing on the stumble at temperature , anyway it looks like a knock sensor, which one? any help would be great and are these two codes connected? as of right now there was no pending codes just the knock/missfire#1 thanx

[maxnix]

Any maintenance history.

[reidness]

i have a firestone recipt from aug of 09 that said it performed a 100k service, platinum plugs?{what kind?} fuel system flush, air filter. I just changed the fuel filter and oil, she idles soooo nice and rides great, realy a sweet 2 owner car, anyway im not sure what is the best way to procede to get her up and running good without breaking the bank, im a tech in the dental equipment/computer field so im willing to get down and dirty but i just dont want to start swaping parts i would like to procede with a good thought out plan of attack! thanx for the help.

[Q45tech]

Why would you add ISOHEAT when the gasoline you buy already has up to 10% ISOHEAT Eqivalent ETHYL vs. ISOPROPYL ALCOHOL.

Before E10 ISOHEAT was a viable/useful chemical tool. Today with E10 no so sure?

12 ounces vs 2 gallons [256 ounces]...................well at least it probably won't hurt anything.

I would test all coils as they are the weakest component in 1996 - 2001 Q.

[reidness]

sounds good, what is the procedure for coil checking? and that would give me a knock code? thanx

[qship96]

Why would you add ISOHEAT when the gasoline you buy already has up to 10% ISOHEAT Eqivalent ETHYL vs. ISOPROPYL ALCOHOL.

Before E10 ISOHEAT was a viable/useful chemical tool. Today with E10 no so sure?

12 ounces vs 2 gallons [256 ounces]...................well at least it probably won't hurt anything.

I would test all coils as they are the weakest component in 1996 - 2001 Q.

Seems I remember YOU were the one pitching iso-heet as necessary for those forced to use e10 fuel not to long ago? I never did understand the need or benefit of adding it to e10 ,just the opposite!

[reidness]

I have an update on my stumble/codes, i went ahead and tried to fix the misfire on the #1, i switched the coil to the #3 plug and cleared the code and bam the # 3 misfired and tossed a code, so i was like great! so i picked up a new coil and while i was at it i got the ngk plugs that the manual recomends. pulled all the plugs installed the new plugs, i was told to gap at.44 so i did hooked it all up and went for a ride!! stumble stumble !! its worse than before and im not sure whats up? a friend has a code reader so i borowed it and it tossed out a p0105, i checked and re checked every hose and plug its all hooked up! it reves great and ideles great but you put it in drive and you have to baby it to get up the street, its bad, if you give it gas it just stumbles until you let off and it will slowley get up to speed. thanx for your help. forgot to mention i also used a maf cleaner when i had it all apart, sprayed but no touchy touchy!
Modified by reidness at 8:09 PM 1/4/2010

[goody90q45]

It sounds like a hose didn't get reconnected. When it happened to me it was the large 3/4" diameter hose that connects to the underside of the air intake tube (MAF to TB). Any air leak past the MAF will cause these symptoms so it would be a good place to start. Good luck.

[maxnix]

...i got the ngk plugs that the manual recomends. pulled all the plugs installed the new plugs, i was told to gap at.44 so i did

If you installed the correct NGK PFR5G-11 plugs, they are pregapped at 1.1mm (~.044") with the electrode gap uniformly parallel at the factory. If you don't have a professional gapping tool, chances are your "adjustment" has not maintained this uniformity of gap.

No maintenance for the EGR valve and tube, IAC valve. TB, plenum or lower runners?

[Sushi Boy]

oh man ... i have the same exact issues as you, reidness. I have yet to try and tackle it... debating actually I just bought the car too.. and already acting up... I have a 2000 q45... i have the knock sensor code, the bank 1 code, the misfire code, and emissions code (o2 sensor) and my valve covers leakin some oil onto the exhaust manifold downpipes...

debating on DIY service and spend who knows how much, but my motor has 213,xxx miles already and I have no clue on the services. OR swap motors,... I found one locally about 1 hour away from my for $699 or $799 from a 1999 q45 and has 88,000 miles complete longblock minus starter n alternator.
Modified by Sushi Boy at 7:56 AM 1/7/2010

[paranoidjack]

Swap the engine??? Are you crazy?

Just because of a valve cover leak, o2 sensor, and other routine maintenance?

213k is nothing for these engines. You could get 300 if proper OCI was followed. I'm tempted to say it wasn't if you have leaking valve covers (one can always hope that's the SECOND set of valve cover gaskets that are leaking).

[Sushi Boy]

Swap the engine??? Are you crazy?

Just because of a valve cover leak, o2 sensor, and other routine maintenance?

213k is nothing for these engines. You could get 300 if proper OCI was followed. I'm tempted to say it wasn't if you have leaking valve covers (one can always hope that's the SECOND set of valve cover gaskets that are leaking).

Figured itd be better? Reidness, how did you test which coil pack was bad?

[reidness]

i just pulled the #1 pack off{the code i had was a misfire #1 cylinder} and put it on the # 3 cylinder and drove it, a day later i got another check light and it was the #3 misfire! anyway that is how i did it, i didnt ever get a knock code. im still addressing the stumble when hot problem! good luck

[maxnix]

im still addressing the stumble when hot problem!

It's most likely one or more coilpacks, especially if intake and fuel system is up to snuff (as OEM new).

[Sushi Boy]

i just pulled the #1 pack off{the code i had was a misfire #1 cylinder} and put it on the # 3 cylinder and drove it, a day later i got another check light and it was the #3 misfire! anyway that is how i did it, i didnt ever get a knock code. im still addressing the stumble when hot problem! good luck

So your saying basically if you get a misfire #1 code its coilpack #1? based on you swapping it to cylinder #3 and you got a misfire #3...

I thought you were getting a knock code before?

[reidness]

well it seams to have taken care of the misfire code, i havent had time to get to the stumble problem, im leaning to a fuel issue maybe injectors?

[Q45tech]

Whether isopropyl will suspend water depends on the amount ALREADY IN the E10 layer and the temperature of the fuel.

Do not confuse the cleaning effect of alcohols with their ability to form a miscible suspension with some amount of water.

After the damage is done by E10 very few chemicals can clean and restore to prior to E10 condition.

That was my point when E10 was first used in your area............after a few months of E10 Isopropyl is near worthless, as the corrosion and rust has already occurred and the alchol susequently has done all it can.

All about timing and that time has long passed for almost everywhere in US.

[Sushi Boy]

well it seams to have taken care of the misfire code, i havent had time to get to the stumble problem, im leaning to a fuel issue maybe injectors?

ok ima try it...

[reidness]

Just wanted to update you on my stumble, i chased bad coils for awile and then i replaced the maf but still had the same acceleration problem, so i picked up 8 new coils from infinitipartsonline and installed them sat and bam no problems, it was a bit of $$ but now she is puring like she should with the ngk plugs i spent another $90 on. anyway if you chase the coil you will waste time and effort, they just kept fooling me! anyway hope this helps out. reid

[Q45tech]

Due to redesign of coils to reduce size and cost, today it is almost always the coils on 97-01 [too few 02-05 to come to a definite conclusion without testing].
Might as well just budget for total replacement evry time you change spark plugs.

[Infinitiguy19]

Would be nice to see if a retrofit of 1990-1994 (95-96?) Q45 coils would work on the 1997-2001 Q45's.

Sure G50 coils have issues if you don't replace the valve cover gaskets or RTV in 90-93 Q45's. Sure they might fail in other rare instances as well but they are far superior to 97-01 coil packs.

But my guess is that the ECU would also need to be tweaked?

[reidness]

one more thing i forgot to mention, when she shifts from 2nd -3rd there is a hasitation? and the hasitation is much more noticable when you are just fethering the gas than when you are giving it the lead foot. I thought is was a symptom of the coil issue but now its clear its not, just wondering if its correctible or just a Q thing. thanx again for the replys. reid

[Infinitiguy19]

When was the transmission fluid last changed?

Whats the condition smell and color?

I would do a couple of drain and refills or you can do the BG machine way as well. But I have to say I did 4 drain and refill and I noticed a 50% difference in shift smoothness so I am convinced for $20 and a $9 low rise oil catch pan you can do it your self. but either way is good.

Matter of fact I would say change the transmission fluid every oil change once you do a full flush because for the cost of 3QT's you can extend the transmission fluid's life which will also increase the transmissions life as well.

But also make sure that all the electrical sensors are working as they should, No Check Engine Light Codes.

[Shane Stahl]

Hey I have the same problem with a 98 Q45 accleration stumble, but when I clear the codes it works great till I stop it again. My TSC and slip light is also on does anybody have a clue what that means