zechsmail

I have a 98 trans am ls1. OK so as title says I'm having multiple misfires solid misfires on 7, and my cars running terrible rich. I just bought an 02 sensor on ebay for bank 2 sensor 1 and it did not clear my code which is for that placement. Have a replacement in the mail. All of these problems began after installing bbk long tube headers and y pipe, With no caback. I removed egr, air pump, air comprsseor and condenser. Soon after 02 went out, unpluuhed from connector and cleared up. Until I cleaned my maf sensor with the wrong chemicals, the problem came back way harder. Missing rough idle pretty significant, started showing cyl 7 misfire, checked plug it was black. Changed plug bought used maf sensor bought new 02 (that didn't work). Plug on cylinder 2 went bad replaced. Lots of very strong smoke from exhaust very rich Found broken pcv line so removed and plugged manifold hole and placed small filters on valve covers. tests I have performed- compression test, fuel pressure test, swapped coils with known working, drove unplugged maf and runs a lot better, tried plugging and unplugging 02 sensors, checked all plugs, looked for broken wires, removed valve covers to check for broken springs all looked completely fine. I found there was a ton of gunked up oil on valve covers so put seafoam in oil currently driving it still only been 10 miles ago. Also used injector cleaner in fuel tank, I don't know what else to do. I've searched these forums for over a week non stop for answers please help.

BRUTL

iTrader: (27)

You need a scan tool that can monitor data, specifically MAF voltage, engine coolant temp, injector pulse width, short term fuel trims, and front and rear O2 voltages. If you're not looking at inputs to the pcm, as well as what the pcm is outputting, then you're just guessing, which will just lead to wasted money.

zechsmail

I work for a Mazda dealership which there scan tool will only read Mazda's and older fords I do not believe it will read gm I have been told. I have been debating taking it to a gm shop. But I have removed so much like ac smog pcv etc I'm wondering if they will not try and lean more toward fixing these "problems' when all I need to do is figure out the cause of misfire, also what is typical diag price for something like this? Thanks for the response by the way

BRUTL

iTrader: (27)

See if anybody in your dealership has a Snap On Solus, Modus, Verus, Ethos+, or Matco, Mac, and OTC all have similar scan tools? All of these will give you the info you need. As far as Diag, Our dealership starts out at 1 hour for driveability related concerns, and it only goes up from there. But like I said, you need to have a look at that data. For what you would pay in Diag, you may be able to get your hands on an Actron scanner that can read some of the data you need to see.

zechsmail

Does autozone rent a tool like that

02z28OK

I drive an 02 z28 auto with only 77, 000 miles. I have been having misfire problems for the last few month not having any luck with a tuenup or chancging cats and oxygen sensors. Any ideas? Mechanic most recently said that he pulled a plug and it was warped?

zechsmail

I need more info to try and help. Although I have the same problem myself lol. Is it a single cylinder that is misfiring or is it random/multiple misfire. What other codes are showing up if any? There are free tests I would I would try to perform first but can't help you without more info. Plus what mods have you done to your car around the time it started acting up

02z28OK

It is all stock. It started right when I changed the starter. It is misfiring on 2, 5,&6. The misfiring cylinders have kinda changed around as I had replaced cats and sensors and what not. It was running really good before I changed the starter out tho

zechsmail

I can only give you limited help since I am in the same boat but what you want to do is as much testing as you can that will not cost you money, at first you should check for any vacuum leaks, including egr valve hoses and connections, and especially your pcv lines they should have a hose that comes off your valve covers and leads up the passenger side to the manifold. Our cars love for these to be broken wiggle the hose in multiple places looking for breaks. Also with either a bottle of soapy water or starter fluid spray other places air travels they will bubble if so. Never tried starter fluid just heard it works. Spray intake manifold and throttle body anything after your mass air flow sensor. These are a good cheap way to start your search, I have other options try this first

LS6427

iTrader: (2)

What brand 02 sensor are you using?

Denso is the choice, especially with hot LTs........Densos do much better than Bosch in the heat department.

And.....1998 PCMs will make the engine run like ****, in many different ways, if the Coolant Temp sensor is starting to fail. And you will not necessarily get a code or light.......

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zechsmail

I got denso 02 waiting is the game now for all my parts should be done soon I will be checking to make sure many parts are working properly by placing new parts in and checking for differences running out of other options

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BRUTL

iTrader: (27)

its not just 98 pcms. The coolant temp sensor is one of the top three inputs in determining injector pulse in most, if not all, modern fuel injection systems.

LS6427

iTrader: (2)

I just remember a lot of 1998 people over the years having the issue with the failing temp sensors......a few people with 99+ cars said they can even drive the car without one installed.

My engine will hardly stay on without one in there.

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zechsmail

Still running terrible actually worse any other ideas

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c-ham

I noticed this started after starter replacement take starter off and make sure crank sensor is plugged in completely. You may have unplugged or broken it whe. Starter was off