thxone

Ok, I have been having a wierd problem that I have not had with this car. For some reason now when I start the car and let it warm up for a bit (after it has not been driven for a while and it has fully cooled) it will idle irratically. I will not drive the car untill the temp gauge moves so I know it is heating up and all that. Once I put it in drive and head down the road it acts like it has no power...I push the gas pedal a quarter to half way and it falls on its face and boggs a bit. If I hold the gas pedal steady while it does that it will do the power loss thing then all of the sudden it will start pulling like normal. Once I am up to speed in top gear (3rd) it will surge just a bit but I can feel the engine slowing then speeding back up...it is wierd. After the car is fully warmed up and the temp gauge is near the middle it is fine. Also when the car is fully warmed up the idle is almost right on the 1,000rpm line in park where it use to be just shy of 900rpm...in drive when warm it idles at 650-700rpm. OH! When the car is "stuttering" if I floor it the problem goes away meaning it starts pulling, making me think it is a part throttle problem.

Other than the valve adjustents and the Ultra Copper I have done nothing to the car, so I can't figure out what the problem is. I have removed connectors and inspected them...they "look" ok but I don't even know for sure which ones to mess with for this kind of problem or what is making it act like this. I did change the oil in the car like two weeks ago and the oil gauge has been kind funny and flutters. It also did not do this before. I went to a 10w30 oil because I had no idea what the car called for. With the old oil the gauge was smooth with throttle imput and didn't move as much, now it is below half on the gauge and when driving is near but just below 90 on the gauge. should I use a single weight oil like straight 30 or go with the 5w30 it calls for?

I should note that when the car is doing its wierd bogging thing that when it does start pulling it is pulling harder than normal which makes me want to fix this problem quickly. It's like every now and then this car tries to show me that it wants to haul *** but only when it is messing up...like it is teasing me! I don't like being teased.

NismoPick

Sounds like it could be several probs... but lets start at: Have you ever adjusted the AFM?

thxone

No I haven't done the AFM, after reading the instructions on how to do so and reading that it could also mess things up if I do it incorrectly makes me weary of doing it...at least at the moment it runs.

NismoPick

It's not hard to do. But I would advise in obtaining an air/fuel gauge to do it.

There are 2 basic things to do:
#1... adjusting the circuit board so the sweeper is fully contacting the carbon track all the time.

#2... adjusting the spring tension to run a lil more rich.

Those 2 things will help your car run better. Also, make sure all vacuum hoses are tightly fitted & have NO cracks. Check timing. Pull your spark plugs & make sure all tips look exactly the same. If one looks diff... you know the prob is that cylinder. Adding a dab of di-electric grease to all electrical connections helps too.

thxone

OK I will give it a shot today. I cant get an air/fuel gauge so it might be best for me not to mess with the richness on the car unless it takes alot of tightening of that screw to mess it up...I could mark the screw with a reference mark though and just tighten a little ( less than a full turn ). The carbon track I should be able to do but the tension for the flapper I am not messin with. Does the AFM "really" make THAT much difference in the car when fixed?

jfairladyz

Did you hose the engine bay down or anything like that??? Go through and check all your connectors for a good connection and no corrosion. Check the cyinder head temp sensor for proper function also.

thxone

No hosing of the engine, but we had alot of rain with the "Alberto" thing...but my hood was closed lol.

duowing

I don't know if it applies to N/As in the same manner as Turbos, but check your Air Regulator. Your car's problems sound pretty similar to my turbo while it's warming up. Do what j told me to do, pull off one of the hoses to the air regulator and look inside of it if it's wide open it's good, if not then that means your air regulator is starting to die out. Basically if you see anything that looks like it might impeded air flow then it's probably bad. Do this before the car has been started, when it's completely cold. Let us know.

WildmaN

Yes the AFM is a crucial part to running of these cars. I know from experience, I had the nightmare of AFM's giving me problems. When I first got my Z running with the other motor back in Feb. He kept fouling the plugs, and I couldn't figure out why. Even after messing with the AFM itself. Swapped the AFM for another one, and woila, he started and ran fine. But in a short time, I had to get another AFM, because it took a crap. Even after I adjusted it. I got another one off E-bay for cheap, adjusted it, and after the dialing in I was suppose to do for emissions. Passed fine, runs great, and basically no more problems. To me, the AFM is a verry delicate piece of equipment that is essential to these Z cars. I mean if the computer cant see it, the car will run rich as crap. Idle terribly, and blow a lot of smoke, because of the dumping of fuel. The AFM from what I have went through, keeps the ECU in check, in dumping the right amount of fuel. Although there are other parts, that contribbute to this.

thxone

Yes as soon as the CD changer is in the glove box I am going to mess with the AFM...where is the "air regulator" on these cars???

NismoPick

smack center top side of the intake manifold... looks just like this:



You really need to get a Haynes manual....

thxone

I know, I ordered it a while back and the parts store still doesn't have it in yet...those ******!!! I paid for it...it should have been here by now. But thank you for the pic.

thxone

Ok just cleaned some connectors and took it around the block, I see some smoke coming out of the tail pipe when I rev it up good. It is kinda whitish smoke but not a super big amount. I also took the connection apart for the O2 sensor while the car was running and nothing happend..is that bad? Is this the kind of stuff the AFM rebuild thing wil fix? It is still hesitating also cold or hot.

Here is a graph of what my engine is doing when I push the gas...the line represents the smoothness of the engine.

Attachment 4800

jfairladyz

Sounds like you're running rich... the AFM can definitely cause that. Also the cylinder head temp. sensor and the O2 sensors are common culprits of this same condition. The O2 sensor really only provides any feedback to the ECU during part throttle. At idle and WOT the ECU doesn't use the O2. So if idle and WOT are fine then that kind of hints at replacing the O2 sensor (or atleast checking to see if it's working).

thxone

OK that is narrowing it down because yes at WOT it is perfectly fine but part throttle is where the problems are and like I said I had the car running and unplugged the O2 sensor and there was no change at all, no off idle, no sputtering...nothing. When I removed each fuel injector connector there was a noticeable difference with each one. I also removed the one connector on the side of the throttle body and it made a difference, in fact the only connector that didn't do anything was the one directly connected to the front of the thermostat housing.

jfairladyz

front of the thermostat housing is the thermotime switch...it ONLY affects the starting of your car. And even then it has to be below a certain temp for it to even affect that. If you have an ohmeter you can also check to make sure your TPS is working properly. Just cause it's working at idle doesn't mean it's working at part throttle. If the TPS is telling the ECU that the throttle is still closed or at WOT when you're actually just cruising then that would cause some hiccups.

thxone

I am going to go at this with the mind set that the problems I am having are not engine problems but sensor problems, so I am going to start replacing various sensors and connectors until I have all new stuff under the hood. I have a couple of questions: 1, will the harness for all the connectors under the hood come out in one piece or does it have to be disconnected from the ECU and then removed so I can solder or crimp in the new connectors and wires..(Injector connectors, sensor connectors) 2, I am going to replace all rubber hoses and vacuum lines, which would be the most important right off the bat? 3, TUNE UP STUFF!!! Cap and rotor, Plug Wires, PCV, EGR, fuel filter, It has new NGK plugs in it, The coil is good. What am I missing guys?

I didn't get a chance to mess with the AFM yesterday but I will today and we will see if that helps. I figure this engine only has 94,000 miles on it so the chances the engine actually being messed up is remote however not impossible but visually and physically the connectors are old and some are falling apart, I have seen the metal parts of most of the connectors and they are corroded and green. Oh and the "blue cover" on the AFM for the fuel richment screw is still there, so maybe that is still set for the stock setting. I will also be setting the timing at between 10 and 12...probably 10. I am looking at having this all fixed by september when I move to Ga.

duowing

Well you said the car pretty much runs fine once it's warmed up right?

thxone

For the most part yes...runs pretty good with minor surging at part throttle at cruising speeds when warmed up...its just that damn running cold driving where it is a mess. But like I said, at WOT it is great with no problems cold or warm.

thxone

Ok so I did the AFM thing about an hour ago, wow it made a difference. It is still doing the serging thing but man the pedal is way more sensitive or should I say smoother feeling. Why is it at three different auto parts stores that I went to, none of them have the fuel filter or PCV in stock? Just curious but how bad can the exhaust leak at the #6 cyl at the head effect the car... I mean it is way worse than it was....would it make the car run rich if not all the exhaust gas is passing over the O2 sensor???

jfairladyz

a leak upstream of the O2 sensor can defintely cause a rich condition. And again, that leak wouldn't affect anything at idle or WOT

If you want to remove the whole engine harness then it does need to be disconnected from the ECU and there is also some things it spiders into over on the passenger side. The easiest thing to do is to just leave the harness connected to the car and remove all the connectors from their sensors and then pull the whole harness over to the driver's side of the car and do the soldering with it still attached to the car. I redid all my connnectors with the harness still in the car. It was a PITA at times though cause I was in the driveway and the days get windy around here.

EDIT: Scratch that, the harness does NOT need to be disconnected from the ECU. It can all be pulled in through the fire wall and removed with the ECU. But it still spiders into the link box and things like that and will need to be removed from those items.

thxone

Good to know, thanks for the info. Kinda makes me a little upset cause that Ultra Copper is STILL holding strong so the leak at the exhaust flange is in check big time but now the one on the head is being a *****. I cant wait till I can get that header!!