92 Rag

Well guys, I've been doing alot of reading and asking questions on here, but this thing is driving me nuts, here's where I'm at:

miss at idle, and above, cruising down the raod at 1500 rpm, steady miss. If I turn the car off, wait 5 seconds, clears right up, idles smoothly, then slowly deteriorates in a minute or 2. Exhaust stinks when idling in garage, don't know about driving down road.

Here's the condition of motor:
'92 5L TPI, 5 Speed, 147,000 kms (about 90,000 miles)

New intake manifold gaskets,
new EGR valve,
O2 sensor replaced last year,
new exhaust incl. new cat,
new timing chain and gears,
tps set to spec,
throttle blades set to spec,
timing at 6*,
vacuum is anywhere from 15-22 inches,

Car runs great with o2 unplugged. Car sounds like there's plug wire off, but runs smooth until it warms up, I'm thinking the car runs better on open loop, and goes for a crap once it goes into closed loop. Almost feels like there's too much timing.

With the 5 speed you really notice the miss when driving down the road. Never will stall, always ildles around 750 rpm.

Ok, what do I check next?

TPI-Formula350-

rotten egg smell usally means your cats are on there way out. might be your problem

92 Rag

I agree - but I just put a new cat on it 2 weeks ago.....

I read on here somewhere that it could be running rich, drove it all day today and gas mileage was very good, maybe not quite as good as it was at one time, but still very good.

Also have new pcv on car, all vacuum lines have been gone over.

Scott57350

If you just put new cats on 2 weeks ago, its still ur cats. its normal for them to smell like that when u first get them. It will go away after u drive it more.

cc 82Z-28

iTrader: (7)

One more thing to remember is that you should of changed the 02 sensor when you changed the cat. If your car is running rich, you will ruin that new cat in no time, trust me, I know from experience. You would'nt want to put a new cat right away would you?

92 Rag

nope, don't want to wreck the cat, but there should be warranty on it anyway.

So, if the car is running rich, what should I be doing about it?

Should I get anothe new o2?

Can you adjust mixture?

I should probably check fuel press. too?

Thanks guys

DENN_SHAH

iTrader: (1)

you said you have a miss, that right there will make the exhaust rich & will over heat the cats & can cause a rotten egg odor. if the gas has too much sulfur in it that can also cause the odor too. even a lean misfire will cause too much unburned fuel in the exhaust. yes, check the fuel pressure, if it is good then pull the vacuum line to the regulator & see if it may be leaking. if it looks good then see if you can find the misfire.
you said it does it warm & at idle, so that's good, it should make it easier to find. to find it pull the injector connectors 1 at a time & watch & listen to the motor, make a note on any cylinders that it doesn't make any or much of a change to, put the connector back on before you go to the next injector. you may want to unplug the idle air control so the ecm doesn't mess with the idle speed. do each cylinder before going to the next step. once you find which cylinders have a problem, check the plugs, wires, & injectors on those cylinders. if everything checks good you may need to pull the fuel rail & check the injectors for leaks, spray pattern & volume.

92 Rag

thanks denn....

I checked all the injectors, they all seem to be firing, I guess that maybe I should check resistance as well, not sure what the values should be though....

Anyway, I plugged the hole in the throttle body where the iac hole is, the car idles great with it plugged, so....

my next question is:

Is the iac not extending fully? to close off all the air at idle?

it idles around 500 with the iac hole plugged.

Had the iac out as well, the plunger fell out in my hands when I pulled it out,

Help

cc 82Z-28

iTrader: (7)

One more thing I forgot, I saw a news report about a week ago talking about a brand of gasoline that has affected a whole bunch of stations around the nation that has a very high sulfer content to it and is causing problems with peoples vehicles. They said the offending gas would have to removed. Sorry I don't remember the name of the brand of gas, but it sounds like it really plays havoc on those who use it.

92 Rag

should the iac be totally blocking off all incoming air when the car is warm?

Mine is still letting quite a bit of air in=lumpy idle(750 rpm), if I block the hole off, it idles lower and smoother -around 600rpm.
That sounds right to me.

Also , I get a small shake around 900-1000 rpm, very annoying on the take-off from a dead stop.

Red Devil

Probably a combo of things. Listen to denn and cc and get some fresh gas. You may have a bad batch. The rotten egg smell is the sulpher burning. Volcanos smell just like that. Stinky!!

As for the IAC Vader had a very good write up a while back, but knowing him, he's probably posted it again and again for repeats. Do a search in gen tech with iac or iac and plunger, and Vader. it should come up. Worth the search.

fisherbody86

It sounds like your car is running lean. That rotten egg smell is tell tale lean condition. If your oxygen sensor checks out to be functioning properly, I would first suspect a bad MAP sensor. I have seen this before, once with a mass air car and once with a speed density car. The mass air was the culpret on the one, and the MAP on the other. In both cases, the ECM was recieving imporper information on how much air was being injested and was mis-fueling the engine. But in both cases, in open loop the car would run okay because the bad sensors weren't affecting A/F ratio. Both experienced lean misfires and a rotten egg smell.

Since your car is speed density, check the MAP sensor.

92 Rag

thanks fisher body....

now, how do I test the thing, can I take it into a parts store and have it tested? or is there another way?

sounds very interesting, and the only thing I have delved into...

really sounds like that could be it.

fisherbody86

I don't have the exact numbers in front of me, but testing it involves a multimeter and a handheld vacuum pump. Measuring the resistance between two terminals while appling different amounts of vacuum to the sensor will tell you if it is working or not. I just don't know which two terminals and what the resistances should be off hand.

That information is in the service manual for your car. You can go to a local library, chances are they have either a haynes, chiltons, or even the GM manual on the shelf. I can get that for you if you need me to, I have ALLDATA at work.

Or you could always try the "substitute known good part" test. Go buy one for $40 at NAPA, keep the recipt, throw it on, and if it doens't fix the problem just return it. That's what I would do if I were you.

92 Rag

thanks man....

I'm going to spend acouple of hours on it today, I'll let you know what happens.

I'm still concerned my vacuum is a little low though, and still maybe too much air getting thru the iac port at idle.

fisherbody86

How much vacuum do you pull down at idle? 18-20 "mg is ideal. If you have a vacuum leak, the MAP could be misreading the absolute pressure inside the manifold. If you think you have a vacuum leak, spray water on the engine while it's running. You will be able to hear the water being sucked in and pinpoint the leak.

The vacuum lines that run along the drivers side fender, behind the washer resivoir and brake booster tend to dryrot and crack. Also, the two hard vacuum lines on the passenger side of the enigne that go to the heater control module and something else (I forget what it is) brake where they go into the wire loom under the coil.

92 Rag

thanks....

I think I'm going to check those hard vac lines going under the coil, seems to me when I was wiggling them around one day, the motor sped up and slowed down, my vac is only at 15-16 inches so I think there's a leak somewhere. I can't see very well under there, but one of them may be cracked. The others going to the cruise I have checked, they seem good.

Also, I'm using an aftermarket PCV, I read on here that the gm ones may be different?

BTW, the car runs like HELL when I get on it, no miss, and pulls like crazy.

92 Rag

BTW, does the map sensor just draw some vac off the plenum?

That's all that I can see that it does, I thought they had a wire in there that heated up? or is that a MAF ?

D's89IROCZ

thats the MAF

TMX

My .02, for what it's worth..

92 Rag, if the car is still missing at idle, and you can't find a vacuum leak, I would go back to DENN_SHAH's post, determine exactly which cylinder is dropping out on you (if it's a steady miss, unplugging the injectors one at a time with the engine running should readily show the misfiring cylinder), and pull the corresponding spark plug to see what it looks like. Black and sooty means overly rich, fuel soaked could mean rich or no spark, and bright white and dry could indicate a lean condition in that cylinder. In any case, the rotten egg smell is not normal under any circumstances, and is generally caused by excessive unburned fuel making it to the cat - whether it's getting there due to a rich condition or lean misfire is something that reading the plug from the dead cylinder will help you determine.

plug chart

One other thing to keep in mind is that even though your new cat has a warranty, the warranty will be void if the cat is damaged due to the running condition of the engine. Be careful.

-Bob

92 Rag

Alright guys, this map sensor is a possiblre target, I had checked everything else, but it seems to have something going on.

I removed the vac line to it, and plugged the one in the plenom, the car exibited the symptons that it usually does when it warms up, such as misfire and popping in the exhaust as well as a stumble/shake right off idle at 800-1000 rpms
Think maybe I should order a Map sensor?

sounds like it to me....

92 Rag

I just had it out for a rip;

the car pulls smooth and strong thru the gears - no missfire or lugging, sounds excellent with the new exhaust on it,

I put a little longer vac line to the MAP, and the car does feel a little better.

I can feel a bit of a misfire/surging when I get up to speed and hold the speed, it smooths ot once again (with a deeper exhaust note) when I get back on the gas -even slightly.

May be running too lean. The car runs real nice with the 02 unplugged (richer).


Also , I know there is still a problem with that shake right off idle.
Really shakes bad with the Map vac line off and plugged.

may go for a map sensor Wed., unless somebody else has a better idea.

92 Rag

changed map sensor and air temp sensor in plenom, no change.

I've just about had it with this thing.

I wish I could just run the car in open loop, it runs perfect.

I'm going to take a break from it for awhile, hoping that maybe an answer will surface.

thanks for all your help and ideas so-far.

gold0_9

im having the same problem. exactly. i ordered myself an auto
e-ray 3000, maybe this will better my chances. i have a 305
tpi, speed density ( no maf ). i'll let you know of ant luck.

Hobie1Konobe

So what happened how was it solved I’m having issues on my sixth gen Accord

OrangeBird

iTrader: (1)

You will need a Honda forum to get your answer , this forum is only for third generation GM F body cars , 1982/1992 Chevy Camaro / Pontiac Firebird .

PS , when you get to that Honda forum , have a little look see at the dates of the threads your bumping , this thread at a full 15 YEARS old has gone a bit , , moldy ....