OK, bought my 2k GXE about 7 months ago w/80k miles on it.

Within a couple months of buying it I put on a budget Y-pipe, K&N air filter, cat back exhaust, and made some suspension improvements.

Car was in a weird front end accident that caused some suspension probs, but engine seemed ok.

Now, it's running _real_ rough sometimes when it's cold, esp when it's cold outside. It generally improves once the engine bay temp increases. My check engine light has been on since a little while before I noticed the rough running.

When it's running rough I've got less than 1/2 the normal power, and I _always_ lose power above 3500 rpm.

The autozone diagnostic computer says the engine code is "engine misfiring". I followed the procedure in the Haynes manual for checking the coilpacks which entailed checking continuity and resistivity across the 1 and 2 terminals of each pack. They all had appropriate readings and were w/i close range of eachother, so according to Haynes they should be OK.

Matt98se recommended pulling coilpack wires one at a time while the engine is running rough and see if any of them don't have an effect and that would be the bad one. Haven't had a chance to do that yet.

I was about to do that tonight and I was revving the engine w/the throttle cable from w/i the engine bay and I noticed a loud sucking sound whenever the engine was revved. I'm guessing this might mean a vacuum leak? According to Haynes, that is one of the potential causes of my power problems but I'm not sure how that would be related to the "engine misfiring" diag message, or what info the computer uses to determine this is happening.

Also, my K&N airfilter is noticable dirty. I'll pickup a cleaning kit for that tomorrow.

As far as the sucking sound goes, does anyone know if there are any notorious leak spots, or am I pretty much on my own for tracing it down by locating the sound?

Also, is there anything I'm missing at this point?

Any info is ___greatly___ appreciated!!!!!

THANKS!!!

-Jacob

 

I should also add, that every now and then the transmission will go out of engagement (torque converter?) after sitting at a stop light for a minute or two.

The engine revs freely up to a point where something catches and reengages. I had a valve body mod done by the guy in Houston on the northwest side (forget his name at the moment) and I've got Mobil 1 synth tranny fluid.

When I got the car back from the shop, there was more tranny fluid in it than there should've been, but I haven't had a chance to take it out yet.

-jacob

 

Easy stuff first. The vavlebody was installed incorrectly. There is a write up on it, and iirc theres mention of your very problem occuring if you don't reinstall some component properly.

Engine problems. The engine should sound very continuous. If it sounds like a cylinder is not firing, then either one or more of the ignition coils are bad. Leave the engine running and unplug one harness at a time. If the coil is working properly, there should be a notable change in idle. When you unplug one and there is no idle change, that's your bad coil.

You have an intake installed. When you rev the engine, it sucks in air through the filter. That's the sucking noise you heard.

I have a similar mileage 00 SE, MAF and an ignition coil went bad when my car suffered very similar problems to what you are describing. But prior to the ignition coil going bad, the MAF was already bad. Car took much longer to wind out gears than it should due to loss of power. Most notable powerloss was above 3500rpm. The bad MAF never through any codes and the first code that came up was cylinder misfire, and a lean condition on bank 1.

TK

 

Thanks for the info. I'll unplug a coil at a time next time it's running rough. I'll search for info on the valve body, but that problem didn't start until about 4 months after I installed it.

Thanks again!!!!

-jacob

 

Also, is there a way to test the MAF w/o buying a new one first? Thanks!!!

-jacob

 

My suggestion would be to replace all six coils, and if the problem still exist then get a new MAF sensor.

 

What if only one coil is bad, then he buys an extra 5 coils for no reason.

The MAF going bad shouldn't cause the car to run roughly, aka cylinder not firing. It would be more of a power loss problem. Check one thing at a time and single out the problem. Do the coil check, if you find a faulty ignition coil, get one to replace that one, or however many are bad. Once that problems ceases, if the power loss above 3500rpm is still present then go ahead and change the MAF.

TK

 

My understanding is that the coils in the 99-00 max/I30 are faulty so when they start to go it is best to just replace all six. Some have also said that at idle the coils may test fine but don't work "under load", so it's often hard to tell exactly which coil or coils are bad.

 

UPDATE....

According to HaYnes, the MAF should be driven by a full 12V one the red wire, and the first thing to do in testing the MAF is to verify the wire is getting full voltage.

I checked mine and I'm only getting 5V at the red terminal. Checked the battery itself, and it's got a full 12V.

Does anyone know for sure what the MAF is supposed to get in order to adequately heat the wire?

THANKS!!!!!

-jacob

 

Also, on the coil packs, is it best to get/avoid particular brands? I was just gonna go to Autozone and pickup a set of 6 = $300.

I've been trying SkylineGTR's suggestion but the problem is so intermittent (seems it's only there when I don't have time to check it or when I'm passing, heh) I haven't been able to get conclusive results.

-Jacob

 

Damn, autozone says the main parts warehouse is out of them. Dealer wants $78/piece.

 

contact dave b

 

Ya, David B will send then shipped for ~300.oo

 

sweet. thanks!

-jacob

 

I found this which may help you out on this issue:

This is a "How to" write up with links to pictures. (Sorry I don't know how to upload them, if this becomes a link in the FAQ sticky, I will edit and try to get moderator help) SO here it goes:
Your MAF is located on your air box between your Throttle body and Air filter. It sets about 8-12 inches back from the air filter itself. It has 2 Torx screws holding it down.
The 4 wires are color coated as follows (2000 model) from right to left. (From passenger side to driver side) (Left to right in the pictures)
White wire: Signal wire - This will change as your speed/load changes - This is the wire the ECU/TCM takes information from to alter shifts, A/F ratio, timing,etc.
Red wire : Reference wire - This should stay the same. This wire is from a hot source and has some sort of resistor to send only 5 V to the wire.
Black wire: Ground wire - Should be .05 or less VD from battery ground.
Red wire w/ Green strip: power wire - Should be battery voltage.

Thanks to puppetMaster for the MAF signal specs they are as follows.
All readings are at Engine operating temp, and no load. ( radio, head lights, ac, heat off)
SIGNAL WIRE (white wire)
Idle: 1.1V-1.5V --alldata says 1.2 - 1.8 volt
2500 RPM: 1.7V - 2.4V
Reference Wire (Red wire): should be @ or just below 5 V. If this is low your Maf signal wire will send low #'s to the ECU.
GROUND WIRE (black wire) .05V or less - SHould not change more than .02 volts with load or engine speed increase.
POWER WIRE (red with green strip) Battery voltage. (13 - 15V) Should be close to the voltage you get when checking battery terminal to terminal. Alldata says 11-14.- IMO- If you have 11V your battery is either dead or you have an electrical problem..... again-IMO.
I couldn't find any specs for the ground or reference so these are universal specs among all domestic/import MAF sensors.
For some pictures here is a link.
http://www.cardomain.com/ride/2195944/2

 

See my post below..

 

???? It's been 4 years since the last post. Hopefully, he's fixed the problem by now.

 

elohel

 

when you search...check the date before you provide advice to a 4 year old problem...just saying

 

Sooner or later you'll be a fan of people who help by leaving complete detailed data regardless of the date.. Maybe someone ELSE.. needs the info.. like me.. thanks ansbanks