Motor issue...

[MclarenF1]

Hey everyone. I haven't posted here in awhile. I hope everyone is doing okay.

I'm writing because of a miss my Z has just developed. I know that several posts have been written on this subject, but the circumstances under which my motor misfires are a little different from the other posts that I have read. My car runs fine when cruising, but when 3/4 to full throttle is applied between @ 2300 - 3300 rpm, there is severe hesitation accompanied by audible valve rattling.

The engine has 59K on it, so the time for the 60k tune-up has come. Before I begin the tune up, though, I just wondered if anyone knows of any sensors that might cause the exact problem I have described. I know that throttle position units are prone to go bad, but the problems with my motor aren't really indicative of a bad TPS. Likewise, bad plugs usually don't cause a consistent miss between a set rpm range. The other possible culprit- a clogged fuel filter- usually causes a miss at part throttle, so I doubt that's the problem. Another option that comes to mind is the fuel pump. It's been sporadically buzzing over the past couple of months, so I wonder if it's going bad and beginning to falter under full throttle loads.

Anyway, sorry for the long post. I realize that 9/10s of these issues have been discussed at some length before, but I wanted to share my exact problem just in case it rings a bell with another member. I appreciate the help and input.

[k3smostwanted]

Don't put those thing you mentioned past it. It could very well be any of those things.

Though it does not sound like spark plugs this would be the very first thing i checked. Even if the spark plugs weren't the problem you can tell alot from looking at them. For example, if it is in deed a fuel related problem like you suggested, your spark plugs would indicate by their wear and color appearance that you have been running quite lean or quite rich. So by checking the plugs, you could eliminate or narrow down your problem even more. Also, with the unique ignition system of the Z32, one bad spark plug could cause a very cinsistent problem. Could also be a bad Coil Pack as far as that matter goes. Just an idea...

TPS Sensor is a tricky little sensor that is a main cause for alot of Z32 Engine troubles. I wouldn't put any problem past this sensor, especially since it is happening at the same RPM range consistently.

Another thing it may be is the AAC Valve or the FICD solenoid within...but it could be a number of sensors.

Also, i would get that timing belt changed very soon...I don't know if it is even possible for the timing belt to slip a tooth but timing could also cause a consistent problem.

Anyways, I would definitely start by pulling the plugs and see how they look. Also, run some fuel injector cleaner through it on the next tank of gas, could just as easily be a partially caused fuel injector that at full throttle, the fuel just isn't getting through.

Just some ideas...

[ZedEx]

Auto Crossing a Zed... Now there's something I haven't thought of yet

*Throws For Sale signs on Civic*

-Wes

[freakonaleash1187]

like k3 said, i wouldnt put anything of the things you mentioned past you. you can tell a lot by looking at your spark plugs, and hell, if they havent been replaced lately, might as well replace them, its cheap and always makes the engine run a little better. have you ran an ecu diagnostics yet?

[MclarenF1]

Thanks for the advice, guys.

Oddly (and frustratingly) enough, I drove my car to work and back this morning and it is doing just fine. I absolutely HATE trying to find the cause of a miss- especially a sporadic one. It will probably run just fine while I'm working on it, and then show up when I'm 700 miles from home. My luck...

I haven't run a diagnostic test on it yet, and since I don't have a OBD II reader (required for a 96 model), I'll either have to buck up and buy one or take it to the dealer. First I'm going to do a tune up and see if the miss goes away. If not, I'll go ahead and run a diagnostic check. As far as plugs go, I do have one question: Has anyone used a spark plug other than the OEM NGK plugs from the Nissan dealer? I was thinking about using some Bosch platinums since I have had good look with them in the past and they are about half the price of the NGKs. I have also heard that good ole' copper core plugs actually fire better than the platinums, but just don't last as long. I'm not trying to be a cheap ass here, but if another plug will do as good or better a job than the NGK at half the price, I don't see the point in throwing my money away.

As for autocrossing, I see a few Zs on the course every once in a while. Oddly enough, I always see NAs. I have yet to see a turbo. (But I'll change that within the next year and a half or so! ) The NA runs in the F stock class with Mustang GTs and Camaro Z28s. I usually (but certainly not always) whoop up on the Mustangs, but a well driven late model Z28 will be hard to beat until I get some decent tires. I'd probably have to say that a well set up and driven Civic is a better autocross car. If the course opens up, though, the tables tend to turn. As I'm sure you are very aware of, Zs are a little on the chubby side when it comes to autocross duties.

Ahhh... one other random autoX comment. I think I'm going to try running another car next year. A 1998 Mercedes C43 AMG. Now that should be interesting. I'm not even sure where it will be classed. It would be absolutely awesome if I ended up running against regular C230s. I have searched the rule book and can't find the C43 listed anywhere.

[freakonaleash1187]

i am using the bosch spark plugs, they work just fine, although i have never had any experience with the NGK spark plugs. and about getting an OBDII reader, your local auto parts store should lend you one, you just have to give them a $150 check, and then when you return the reader, they give you the check back. at least thats what they do around here.

and if anybody thinks that Z's dont auto-x, i auto-x my Z, and i have 3 friends with TTZ's that auto-x. so we have 4 Z32's (3 of them twin turbo) and usually 3-4 Z33's, and 1-2 Z31's that auto-x in kansas city.

[crx1989]

Just putting in my 2 cents. I had the same problem with one of my past cars where it would drive fine until I got on the throttle a bit and it would spudder and hesitate till I replaced the plugs then it back to normal. May not be your problem. It was a turbo and went through plugs every 20k miles. Just my 2 cents.

[MclarenF1]

I'd like to thank everyone again for their responses. I'm getting ready to do my tune-up, but the car is actually running great right now. I think I might have fallen victim to skank gas. They put in a new Mobile station not too far from me, so I thought, "Hey! If I have had good luck with their motor oil, why not try their gasoline?" I ran my last tank to empty and went back to my usual Shell station. Everything has been hunky dory ever since.

BTW, I still doubt it was a problem with the brand of gasoline. I am told brand new stations sometimes have problems with water in their tanks. Oh well.

[freakonaleash1187]

well, im not saying that this happened but it could of, are you sure you put 91-93 octane in? or did you unaccidently put 87 octane in?

[MclarenF1]

Originally Posted by freakonaleash1187

well, im not saying that this happened but it could of, are you sure you put 91-93 octane in? or did you unaccidently put 87 octane in?

At first I thought that I might have done that, and the idea bugged me so badly that I went back to the station to take a second look at their pumps. The grades are really well marked, so it doesn't seem like something I would have done. But then again, I guess anything's possible. The problem started over the course of two or three consecutive fill ups, so it also seems like the problem should have rectified itself after my last visit to the station.

Still, I'm by no means perfect (even though I like to pretend sometimes), so I won't say that your suggestion isn't possible...