HibachiZ28

iTrader: (5)

This is for my 98, my daily driver. I was driving in this morning to work and I noticed some hesitation in 6th gear at 65 MPH. Wasn't a big deal I thought. Then, I noticed it at lower gear, and now while accelerating in every gear. It's like a full auto AK-47, for example, in terms of rate (not loudness). It does not happen at idle while revving.

My SES light has been on for months now. It's telling me the driver side cat is bad. On my drive to/from the Hamptons I hit 2389048923480234 bumps, pot holes, etc., mainly on the Belt Parkway & Staten Island Expressway. Is it possible it rattled my cat apart and is now clogged up?

I don't think it's bad gas, but who knows. I've always run Sunoco 93 octane gas. Over the weekend I was in the Hamptons and had to fill with Hess gas. I ran through that tank from Sunday to yesterday, and filled up with Sunoco.

Also thinking possibly plugs? I have 107,XXX miles and do not think that the prior owner changed the plugs or wires.

Any recommendations are appreciated. Thanks.

EDIT: Check Post #67 (Page 4) for an update.

LS1121

iTrader: (17)

Yes it's time for plugs and wires. What exactly is the code your getting, that makes you think the cat is bad?

HibachiZ28

iTrader: (5)

Thanks. This is why I think it's the cat: https://ls1tech.com/forums/generatio...t-mpg-yet.html

wssix99

iTrader: (5)

It does sound like a bad/broken cat, but...

Before addressing that, I'd still do a MAF cleaning first. It's dirt cheap, easy to do, and your K&N makes you more likely to fall victim to a contaminated MAF. If that MAF is reading incorrectly, it can cause your air/fuel to be off and throw off the O2's. Its happened to me in the past, but I got a different SES code. (The code you are getting more closely points to a Cat issue.)

HibachiZ28

iTrader: (5)

Thanks. Should I clean my MAF or swap it over from my '01? Not sure what years are the same? I may just swap over the OR-Y from the '01 to the '98, then get a new cat for the '01.

wssix99

iTrader: (5)

I had a K&N soil my MAF and a cleaning with MAF cleaner (specific for the purpose) took care of it and several years, I'm still going strong.

HibachiZ28

iTrader: (5)

Hmm. Well, I got the CRC MAF cleaner. Cleaned it during my lunch break. Still sputtering - mainly under WOT, but it's still there at other points on and off as well...... I'm going to hook up my scan tool and see if it's throwing any other codes.

HibachiZ28

iTrader: (5)

Update: I swapped the de-screened MAF (Which was run with an OE paper filter with SLP intake) from my '01 into the '98. I did find a hose that was open (Drive side front wheel well area). It is now blocked off. Didn't really do much of anything. Still sputters basically the same.

So now I'm on to thinking it's the o2 sensor(s) or cat(s)?

wssix99

iTrader: (5)

BTW - You are incredibly brave to drive from PA/NJ, brave Long Island, and drive to the Hamptons. I did that drive once... Never again. The geography along that route is unique in the world. Its probably the hardest place to get around while being one of the most densely populated...

Have you done a visual inspection of the Cat? If something hit it, you might be able to tell. I'd start by seeing if I could take it off and look at the substrate inside to look for breaks. Do you hear any rattling? (That would be a tell-tale of a broken Cat.)

LS1121

iTrader: (17)

OK so at 107,000 miles when are you going to change those old plugs? I replaced my cats at about 250,000 miles not exactly sure without going thru my paperwork but I know it was ton of miles before I did.

and what a drive that is, I,m glad I do not have to contend with that any more,especially
the part of being robbed at every bridge crossing, lol.

HibachiZ28

iTrader: (5)

Both cats look okay. No rattling that I have heard for, but need to look a bit more and do some minor thumping of the cat to see what I hear. That drive SUCKED. We left here outside of Philly around 8pm, and got to Sag Harbor around 12:15am. Not too bad IMO. I hit every DAMN bump, pothole, construction hole, etc., on the drive out that. That said, I'd rather be with my car in the Hamptons than take a bus or train. I dunno, I love my f-bodies!





109,000 now I'll look at replacing the plugs shortly. Anyone know the GM recommended mileage to replace LS1 plugs? It had been getting worse and worse as of late. I disconnected my driver side, downstream o2 sensor. I just took it out for a cruise and it drives 98% better than before. Some very minor sputtering coming off of idle. A bit more towards the top of the RPM range as well. Still no time to do any work on it as of yet.

wssix99

iTrader: (5)

I just keep on driving up 95, until I get to Maine. (I can buy an entire lobster up there for what a large order of french fries costs in NY.)


Here's some interesting reading on plugs - https://ls1tech.com/forums/general-m...les-i-did.html

HibachiZ28

iTrader: (5)

Nom nom!! Don't get me started on my love for lobster. My g/f, who is a chef btw, has never had a lobster! She went to UVM for 3 years too, and has been to Maine. That needs to change! Oh, and we're both divers too... so wtf? haha.

I'll check the plugs link, thanks!

Here's an update: I unplugged the driver side, downstream o2. The car runs about 95% better than it does with the o2 plugged in. So this means it's most likely a cat, or one of those o2 sensors on the driver side, correct?

wssix99

iTrader: (5)

I don't think I've seen any good definitive information on this. Theoretically... the downstream sensor should just tell you when you have a good/bad cat and should have nothing to do with driveability. But, I have seen GM statements that the readings are put into consideration for the PCM calculations. I don't think I've seen any info on to what degree this plays a part.

HibachiZ28

iTrader: (5)

Hmm, beautiful. I'll talk to my tech buddy when he gets in to work today and see what he thinks. I might just give in and purchase an OR-Y.

homerz28

i got this EXACT problem. replaced the plugs and wires. no luck. got a guy with a reader and we plugged it up and took it down the road and the reader said cylinder #3 misfire. so i bought a new coil and put on it. no help.

But mine will backfire a little when you put it under load. Does yours? Wouldn't this mean that it's getting the fuel, and just not igniting it? This might rule out the injector. I don't know.
I also had a mechanic clean my MAF and got it reading right. Don't understand too much about them but he said it was reading bad, but now it's reading good, and it didn't change my issue.

P.S. i have LTs with no cats.

HibachiZ28

iTrader: (5)

Thanks for the info, Homer.

Let me add to this. I drove the car a few days last week. Rode the bike on Friday. Took my Jeep out on Saturday. Then yesterday I drove the car again (Put about 2 hours of driving on it). No real issues that haven't been listed above.

Then, this morning, on my way to work at 10am, the car started to idle like **** (Approx. 5 mins into the drive, while sitting at a light). It sounded like it was missing. I continued to drive as I was late to work ... the CEL light started to flash and it was obviously misfiring, but was not driving horribly bad. Again, didn't want to stop since I was late to work. After approximately 5-10 minutes of highway driving the CEL light stopped flashing and the miss was gone. I drove the rest of the way to work (Approx. 15 minutes) without issue. I'm going to grab the OBD reader now to see what code it's throwing...

HibachiZ28

iTrader: (5)

New codes are:
P0300 - Random misfire detected
P0140 - o2 circuit blah blah (from when I disconnected the o2 sensor)

chrysler kid

iTrader: (14)

Replace the plugs and wires then get back to us

HibachiZ28

iTrader: (5)

It's on the list. This weekend I'm doing a steering box, sway bar disco's and other crap on the Jeep. I need to thin the heard... one of the TA's needs to go, and possibly the bike...