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pigeon wrote:Datsun1500 wrote:You also realize there is no lemon law for used cars, right? It's your problem now. I would look into seeing what the easy fix is.
Depends on the state - there is a used care lemon law in NY.
yeah, it's called a Louisville Slugger. 
I have an '99 with 130k with a new catalytic converter, coil packs, plugs and wires that is showing P0421's (pre cat effiency) and a few P0300's (intermittent misfires).
I also noticed that the idle is a little rough, but if I turn on the ac, it idles smoothly at 1k rpm (about 100rpm higher than non ac idle).
I'm guessing the misfires are causing the cat CEL, but don't see any obvious probs that are causing the misfires. Zero misfires under load or higher rpm, just at idle...
1999s are prone to coil problems. However, if you have a crank or cam sensor that's not reading quite right it might throw a misfire. The cat code is probably a byproduct.
loudes13 wrote:I also noticed that the idle is a little rough, but if I turn on the ac, it idles smoothly at 1k rpm (about 100rpm higher than non ac idle).
I feel like this was just mentioned elsewhere ... ? The low (non a/c) idle wasn't allowing the O2 sensor to heat sufficiently. When the a/c kicked on, the increased idle was just enough to heat the sensor ... new O2 sensor solved the issue.
Is there a procedure to test the coil pack?
Well, joy of joys. The Miata has been in the shop since last Friday. It's now throwing an intermittent fault code. First shop couldn't figure it out. Still have heard back about the second shop. I guess there's a lesson in here somewhere...
GI_Drewsifer wrote:I guess there's a lesson in here somewhere...
Find a way to collect insurance money?
J/K...
OK, now I'm really worried. The second shop cleared the fault and then couldn't get it to come back. So I went and got it. They said as soon as the fault came back to bring it right back. Not twenty minutes later the light was back. Took it back to the shop, the ran the code, checked under the hood, and then wouldn't tell me what was wrong. They said they would call the dealer, and the dealer would call me. Should I be worried about this?! They let me drive the car home. It ran alright. Worry worry worry...
I guess the dealer is paying for the diagnostics but I still find it a little strange that they wouldn't tell you...
As it happens, my '99 is having ignition issues too. From what I've been reading, wacky symptoms like these have often to do with the coil pack (in '99/'00) or the crank/cam sensors. I'm curious to know what code the car is currently throwing, and what the dealer's diagnosis will be.
nderwater wrote:As it happens, my '99 is having ignition issues too. From what I've been reading, wacky symptoms like these have often to do with the coil pack (in '99/'00) or the crank/cam sensors. I'm curious to know what code the car is currently throwing, and what the dealer's diagnosis will be.
I saw on Miata.net that the coilpack was fixed by 01. They seemed to think it was unlikely, although the symptoms did seem to fit.
BoxheadTim said:I guess the dealer is paying for the diagnostics but I still find it a little strange that they wouldn't tell you...
I figure that's their way of saying, "Your car is about to explode".
Yet another update.
So the dealer says the most common fix for the code he found was to change the oil. The dealer called me and explained that supposedly running too thick motor oil has gummed up a sensor that effects engine timing. So right now it's getting a fresh bath in 5W20. Is this even possibly true?!
Wow. That was one from left field.
GI_Drewsifer wrote:Yet another update.
So the dealer says the most common fix for the code he found was to change the oil. The dealer called me and explained that supposedly running too thick motor oil has gummed up a sensor that effects engine timing. So right now it's getting a fresh bath in 5W20. Is this even possibly true?!
Whiskey.
Tango.
Foxtrot.
...
GI_Drewsifer wrote:Yet another update.
So the dealer says the most common fix for the code he found was to change the oil. The dealer called me and explained that supposedly running too thick motor oil has gummed up a sensor that effects engine timing. So right now it's getting a fresh bath in 5W20. Is this even possibly true?!
Unless you've been trying to run it on non-detergent stright 50 oil I'd find this very hard to believe.
The sensor that effects engine timing is located outside of the crankcase! You could be running peanut butter & it wouldnt care (the bearings might though :)
I call shenanigans!
Kendall
As do I. This was how the dealer explained it to me, and I'm not sure he understands cars. So there's a chance something got lost between me and the shop. I should pick up the car on Monday. If that happens I'm gonna swing by the shop and ask him to explain the problem to me.
A 'cat code' would be a PO720 or 721, catalyst efficiency code. Bad O2 sensors (mostly the downstream one) can set the same code.
A car that's been sitting a long time which on startup, has a crappy idle... I'm going to vote a gummy throttle body. ECMs will lose the memory of idle control if the battery goes dead. Fords and VWs were famous for that; the carbon and fuel residue accumulation in the TB and idle air control get rock hard, disconnect thbattery or let it go dead and the ECM has a hard time learning how to make it idle. Once engine heat softens the goo, it starts idling better. Scrub the TB and IAC with lots of carb cleaner and an old toothbrush, then fire it up and run it for a while.
The other possibility is a vacuum leak which will set not only cat codes and O2 codes but sometimes a PO101 mass air flow code. Vacuum leaks don't generally fix themselves, though. IIRC the MAF on that car is connected to the TB by the air intake hose, if it's cracked etc it will do that. Again, they don't generally fix themselves.
Another long shot: weirdo nonsensical codes and random crappy running on a DOHC engine can come from one cam having jumped time. How's the timing belt?
