Idle Problem

[RedCar]

Hey guys first post!!! I have a 1995 GTP and I'm having a problem with the idle surging from 700-900 RPM in gear and at neutral. The exhaust also smells rich. I've changed fuel filter, plugs, and wires. The car also surges a little bit during crusing but only about 50 RPM it seems like. Any help is appreciated. THX!

[SappySE107]

How old is your O2 sensor? Idle will flucuate a little, but this change hwile cruising i don't understand, especially how you can tell 50 RPM

[RedCar]

The 02's are old 130000 miles on the car... The car acts if the idle is trying to keep a steady RPM speed but it cant.

The surging during cruising is really hard to tell what RPM it goes to. It is a slight surge but it is noticable and happens often: around 2500 to 3000RPM seems to be the worst. The car is getting only about 14-15MPG in city driving. I need to get it smogged but I think it will fail because of how rich its running at idle. I havent had the car very long so I dont what is normal and what isnt.

[SappySE107]

new wires, plugs, and O2 are probably gonna fix it. Maybe O2 alone but if they are all old that is a real problem for the car to operate properly.

[RedCar]

the wires and plugs are new but i'll try new O2's and see what happens. Thx for you help.

[napatiger]

The O2 sensor is a bitc...to change, at least on my 95 MC Z34. After it was all said and done, I saw that you can get a loaner tool to remove from like Pep or Kragen.

[Lyle's GTP]

I had the same problem with my 94' GTP. I tried changing the following parts with ALL top quality shit. Plugs, wires, coil packs, TPS sensor, IAC motor, PCV valve, O2 sensor, fuel filter, upper/lower intake gaskets and cleaned upper intake/throttle body.

Now that load of shit did very little if anything, it helped power some, yes, but didn't help the surging idle. But there is one thing that has to be realised about this engine. With this preticular timing setup the timing will fall out of whack over time. Yes, the belt streaches but so does the chain, and is often over looked.

Now to get to the point, I retimed the engine with respect given to the stretched timing chain. How I did this was finding ACTUAL TDC. I put a rod down the #1 cylinder spark plug hole and used a dial micrometer to find "exact" TDC. I then I locked the cams at this postion. Low and behold as soon as I started her up she idled like a dream. NO surging.

So, I definatily recommend this. It's not hard to do and in the 94'+ cars you don't have to remove the belt at all.

Note: This method is not perfectly exact. Because you actually have about 4 degrees of rotation across TDC. But I didn't have a degree wheel to use in conjunction with the dial to set it "dead-on-balls". So, in this case the micrometer had to do. But, the results were pleasing so I won't bitch.

Hope this helps.

Lyle

[RedCar]

Thx Lyle, did yours smell like gas at idle?? My exhaust smells so bad it makes my eyes water. I'll try setting the timing, because I really dont want to start throwing parts at it. Its hard to justify spending a lot of money on a car that isn't worth that much. Im sure it needs 02's just because they are the orginal ones. But I really dont know how a fuel injected car can over fuel this badly.

[dykz34]

If your exhaust smells, it's very possible that it's a timing issue. Also, I believe you only need ONE o2 sensor since your car is OBD1.

[Lyle's GTP]

Well, mine didn't make my eyes water, but it was pretty rich. I would change the timing and the O2 sensor then go from there. Because at least those are the two things we know could be the problem. By the way I think your car only has one O2 sensor. I think the LQ1 didn't get two until 1996.

Lyle