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So I have A 2000 ssei with about 175000 miles and I've had some trouble with misfires lately. It all started randomly one day as I was driving I noticed it seemed to have a cylinder not firing. so I got home and saw that one of my coils was bad. no big deal got another one and it was fine for about a week then It started missing again. I checked the coils again and I had another coil not sending spark to a cylinder. out of frustration I bought the extra 2 coils and new plugs and wires(was overdue for them anyways), and an ICU. This did help the misfire but it still would miss under load(right about when the boost gauge hits positive boost) and completely lose all power until I let off. it seems like all cylinders are missing. also the misfire destroyed my cat so I bought a new cat but didn't install it yet because I heard the misfire can damage it, so I gutted the old one for the time being. I guess I need advice on where I should go from here, any input is appreciated!

I'd think about replacing the TPS (throttle position sensor), but read up on the symptoms of a bad one first and see if it fits what you're experiencing.

Also, clean your MAF (mass air flow) sensor with the appropriate cleaner while you're at it.

I'd also recommend running a fuel system cleaner with your next fill up to make sure your injectors are clean.

(Can you tell I might have been chasing a misfire as well recently? Lol. Mine wasn't as serious as yours though from the sounds of it.)

Namrepus28 wrote:I'd think about replacing the TPS (throttle position sensor), but read up on the symptoms of a bad one first and see if it fits what you're experiencing.

Also, clean your MAF (mass air flow) sensor with the appropriate cleaner while you're at it.

I'd also recommend running a fuel system cleaner with your next fill up to make sure your injectors are clean.

(Can you tell I might have been chasing a misfire as well recently? Lol. Mine wasn't as serious as yours though from the sounds of it.)

I forgot to mention that I picked up a bottle of Lucas injector cleaner when all the problems started and ran it through. I’m starting to think I have a vac leak somewhere, seems to have a slight mis at idle now, and the boost gauge is fluctuating from -10 to -5 at idle which I’m pretty sure isn’t normal. I haven’t driven it for 2 months but I’m pretty sure it didn’t do that before.

I would unplug the Maf and see if the miss changes.

do you have a scantool that pulls live fuel trim and other data?

if yes, post fuel trims at idle, 1500 and 2500 rpm.

also, what is the map reading with key on, engine off?:

if you have a way to scan it, it will tell you what cylinder the missfire is on and you can look closer at that cylinder. could have a bad injector or bad injector connection, vac leak, carbon build up, bad pushrod, bad rocker, many things... hard to say. what codes are you getting?

S

check ebay and the such for a cheap one to start - you can get decent ones to work with an android based phone also: live data capability would be ideal but not crucial.