thadword

When driving around 45 mph my car ('92) always began to act like it's running out of gas. It feels as if it is coughing trying to clear its throat. But once i get around 50 mph and above it's okay again. I've had a tune-up, manifold cleaned. This has been happening since a buddy of mine gave me his vacuum switch valve off his totaled ls 400 ('90-'94) last summer '08. The good news is that my check engine light went off. Any ideas of what it can be?

Lanson

Without waving a magic diagnostic wand I'd say the computer may be an issue, or the air meter.

The computer can act "glitchy" in these older cars due to capacitors leaking in the pcm itself. That's just a thought.

No codes at all, huh?

thadword

I had a diagnostics done at a local lexus dealer and there wasn't anything about a computer problem. My egr modulator was changed so i'm thinking it's the vacuum switch valve. I'm going to let my neighbor's buddy check it out (he's familiar with toyotas and lexuses) right now. So to be continued. Thanks for your response fourthmeal.

thadword

According to my neighbor's buddy, whose a ceritified toyota mechanic too, when we took a test drive and got around 45 mph, of course the car didn't sputter or shake as if it was running out of gas. Anyhow i told him the prognosis and he told me to use better gas (chevron or shell). I was using a local store brand of gas. So i'm going to run this gas out and go back to using better gas. I'll see if this works.

JimsGX

Stick with one of these if possible. I use Shell (93 octane in my area) whenever possible. Chevron is on the list too.

http://www.toptiergas.com/retailers.html

Jim

91LS400LEX

Pour some Robitussin DM down in the tank. lol. J/K

Seriously it sounds like water in the gas.... I had a car have those same symptoms in the past and that was the problem. Good luck!

thadword

Those two gas stations were on my list JimsGx. You read my mind. That cheap gas i was using probably had water in it 91Ls4. Thanks fellas for your time and your good advice.