y33 idle jerk / hesitation discussion (lets fix this!!)

[willko1]

800+ miles no stumble. Maxnix are you using a digital ohm meter? if so you are probably more accurate than the old analog dial arm type. when you switch the leads from the ohm meter on pin 2 & 3 is there a change in reading?

[maxnix]

Yes, I am using a mid level Fluke. Changing probes is about 5Ω difference, so insignificant.

[willko1]

Yes, I am using a mid level Fluke. Changing probes is about 5Ω difference, so insignificant.

Hmm when I switch probes from 2pin to 3pin and vice versa I get a 280ohm difference on the good used coil (subtracting ohms from each other based on resistance level lead change). On the bad coil there is a difference of 3550 ohms. are you testing a new OEM hitachi?

[Jay97240Sx]

Conclusion to my story. I bought brand new coils and plugs and still had the stumble at idle, sometimes the car would shake violently at other times it was a minor shake. I got frustrated and took the car to my local infinity dealership. I met one of the lead mechanics who was very familiar with that model car and owned one himself. He called me the next day and said he figured out what the problem was. I went by later that day paid $150, picked up the car, and the mechanic told me a valve was sticking stifling the engine of air and causing the car to run super rich throwing a o2 code. He recommended i clean the EGR and do a fuel system clean.

The next day i went by my friends shop. We did the fuel system clean and pulled the egr off and cleaned it. Put everything back together, started the car.....no stumble !! great !! Took the car for a test drive, within 5 minutes the stumble was back WTF!!! I donno what possessed me, i decided to use a wrench and tapped the egr....as soon as a i tapped it the stumbling stopped. That weekend i went down to the junkyard and pulled a egr (as well as 6 coils if anybody wants them) off a wrecked 99 with 37k miles. I swapped the new egr over and so far so good no stumble, the car idles perfectly. So folks, if all else fails, check, and double check your egr valve, i would never had thought that this could cause stumble/missing issues.

[paranoidjack]

Wow...thanks for the feedback.

[maxnix]

If it is the EGR, it will return soon.

Why? Because your EGR tube inside the plenum is full of coke (like is burned, not snorted). The only way to get the EGR tube out and clean it is to remove the top plenum.

Cleaning the EGR with strong solvents and a Dremel is sufficient in most cases. Buying a used one is foolish if you are bent on replacing it.

[Jay97240Sx]

Ok, i know nothing about EGR systems. All i know is the one i had was sticking and i replaced it with a used one. I did do a intravenous fuel system clean through the brake booster, would that be enough to clean the coked up plenum etc ?

[maxnix]

No. And that's a bad way to do it. Let me guess. Seafoam, right?

The EGR tube is what is clogged in the plenum. Only recirculated exhaust gases flow through it.

Don't throw away the old EGR valve. Clean it.

[Jay97240Sx]

Nah no seafoam, its the stuff the dealerships etc use. Ill try clean that tube today if its not too much of a headache. I still have my old EGR valve, i usually hold on to stuff for months before i throw them away.

[willko1]

Nah no seafoam, its the stuff the dealerships etc use. Ill try clean that tube today if its not too much of a headache. I still have my old EGR valve, i usually hold on to stuff for months before i throw them away.

Good info! Still no stumble on 2000 q45 110K after 3000+ but have gotten the P1400 code for EGR though so I need to see why its throwing the code but the car runs good even if the Trans shifts weird the first 5 mins of driving I think that some other members said that is normal before warm up.

[tajji101]

My 1999 Q45T has been stumbling at idle and misfire under acceleration. The "Service Engine Soon" light came on and I got a P1320 code. After reading this thread, I've decided to replace all 8 coils. After all the coils were replaced, the car is back to normal, no more stumble and hesitation but the P1320 code came right back. In addition to the P1320 code, TCS Off and Slip stay on. Other than the code, the car runs fine, no more misfiring. What other issue could throw the code after replacing all the coils?

Any suggestion is appreciated.

[ddsmith60]

Did you do an Ohm check of all your replacement coils? Code 1320 I believe will cause the TCS Off and Slip light to stay on. At least it did on my car. Under TCS part of the FSM it says Engine System Based on the signal from ECM, the ABS/TCS control unit judges that the engine control system is malfunctioning. I'm pretty sure 1320 fits into this category. Maybe got a connector problem or a bad new coil.

[tajji101]

Did you do an Ohm check of all your replacement coils? Code 1320 I believe will cause the TCS Off and Slip light to stay on. At least it did on my car. Under TCS part of the FSM it says Engine System Based on the signal from ECM, the ABS/TCS control unit judges that the engine control system is malfunctioning. I'm pretty sure 1320 fits into this category. Maybe got a connector problem or a bad new coil.

Thank you for your reply. I've checked all the new coils and they are all in the 1650 ohm range. I'll take your advice and re-check all the coils and connectors from the coil to the ECM this weekend. I am extremely frustrated by these OBDII codes.

[ddsmith60]

I used the Hitachi coils and I'm pretty sure they Ohmed out in the high 700 to low 800 Ohm range. That Slip on and TCS off had me going when I first got the car but a change of the coils resolved it. I found a few of the old coils Ohmed out in the 1250 range which probably indicated they were the bad coils but it is hard to definitively know unless you can scope each coil. Most of us do not have access to that type of equipment.

[personalp1971]

Wow, I am so glad to see that this is a relatively recent discussion. I I had a very similar problem with my 97Q45. First I seafoamed it. Car got better, than way worse. So I replaced the plugs, I cleaned the MAF, and the iavc-acc, checked the coils, and checked and dielectric greased all the connections. Now, the car runs great at high idle when cold but when it warms up, it will come down to a low idle and then kinda fluctuate for a few seconds and then level out out to smooth. Also if I stomp on the gas or am going up a steep hill at lower speeds it will kinda pop and jerk for a second but as i build speed it gets better. Sorry this is my first post and not sure if it is right to put it here of if i should start a new one or what. I wanted to say thank you to everybody in advance because this whole site has been an amazing help.

[paranoidjack]

You mention when cold it's good and warm it's not. I'd first replace the thermostat (might be obstructing partially, or worse, intermittently) and bleed the system again. Aside from that, we've found on this forum cleaning doesn't always save a MAF - you might want to grab one from a junkyard and swap it out to test. www.car-part.com is great. Good luck!

[personalp1971]

Wow thank you for replying so quick. Let me clarify, it runs better at cold only because of the high idle at first. It runs better overall when it is fully warmed up. The most distrubing part is that when it is cold if i go to accelerate it will start to bog down with a almost violent fluctuating idle. If i throw it in neutral and then kill it and restart it, i can throw it back in gear and it will be fine. But I have to restart it on order for it to fix the idle surging. I am trying to find a MAF locally I think that is a very likely suspect.

[personalp1971]

Can anybody recommend a good q45 mechanic in the SF bay area. I have worked on this car a lot but think maybe a fresh set of hands might help.

[personalp1971]

Well, it seems to be the MAF. tried unplugging it and started her up. purrs perfectly. Idle is a little high, but it is steady and smooth. Plugged the MAF back in and and wham surging wildly. Checked the local junkyard and there is no compatible infiniti MAF's. Does anybody know if any of the Nissan vehicle have compatable MAF's?

[willko1]

Well, it seems to be the MAF. tried unplugging it and started her up. purrs perfectly. Idle is a little high, but it is steady and smooth. Plugged the MAF back in and and wham surging wildly. Checked the local junkyard and there is no compatible infiniti MAF's. Does anybody know if any of the Nissan vehicle have compatable MAF's?

Try some MAF sensor cleaner first and make sure you don't have junk in your air box

[paranoidjack]

Yeah, I've had two MAF's fail on me - second was a junkyard one. They will make the car do all kinds of crazy things, and this is often most apparent when either idling or accelerating. Coasting seems to have shown less trouble with a failing MAF for me.