QuickGS400

So my family has quite a few lexus's throughout, and we love them. I do all the maintenance and have truely enjoyed them. So when my friend who was looking at for a new car, I found him a lexus, checked it out, and he bought it. Now more than anything my reputation is on the line. As this is one of my best friends and their entire extended family are domestic car owners hardcore. I like doing alot of extensive car work with my friends swaping engines, body work, turbo, etc. So this is embarassing since his dad tells me "i told you so blah blah foreign cars etc" So I get streamed and spend an entire weekend on this car and I'm baffled. I've searched and come up with a few ideas so i'd like to ask for some peoples opinions.

Car: 1992 Lexus ES300 with 106,000. Car is all original and probably never had anything ever replaced. It drove well and everything worked. I checked the timing belt and it looked pretty close to as a purchase deal the place would have the timing belt replaced and the water pump.

So after we got it back it just seemed slow, like smoothly slow. No misses or rough driving, just like we were towing another car behind us. Shifting out of 1st is pretty rough but it looks like the mounts.

So I replaced leaking lower intake manifold gaskets, upper intake gasket, valve cover gaskets, spark plug gaskets, NGK spark plugs, oem spark plug wires, changed the trans fluid and filter. And I tapped the catalyic convertor so see if it sounded broken and clogged and I didnt hear any loose pieces. So it drives nicer now, but still slllllllloooooooowwwww

It feels like the cat is clogged just because I had a mercedes that had a clogged one at that is how it felt when driving it.

Though sometimes going up a hill the car just almost seems like it wont make it, the trans doesnt seem to slip because it holds the RPMS, and when flooring it from a dead stop it goes all the way to redline.. slowly, then shifts like it seems like it should. So I am going nuts I can't figure it out.

So does anyone know what kind of exhaust pressue you guys feel at the muffler? Like at idle and when someone is giving it a lot of gas?

Thanks in advance! Sorry so long, I was trying to cover everything.

Tammy

Find a good shop with a newer Sun diagnostic machine. It will indicate an exhaust restriction or a sensor problem and eliminate the guess work.

QuickGS400

But guess work is free.... well besides the cost of all the parts I didn't need.

Thanks for the input... anyone else?

Pheonix

Reset the ECU.
Check the ignition, and the cam timing. I can't tell in your post if yall changed the timing belt, or not. Check it anyway. If you have to, set the crankshaft to 0* on the gauge, pull the valve covers back off & check that the actual cam alignment dots on the intermesh gears are correct. They'll run way off on cam timing, but farther than 3 teeth is a huge change in cam timing - hence, a huge change in the powerband. (21*+)

Check compression & vacuum.
Check the fuel.
Check the plugs (NGK, or Denso ONLY), wires (NO cheap wires), dizzy cap & rotor.



With no extra weight, in good shape it oughta run about 8.3s 0-60, 16.3 1/4 mile. Unless it's a manual, then who knows. Low-mid 15's.

QuickGS400

Hmm, thats what we tried telling the guy who replaced the timing belt. We said that it was off and needed to be retimed and he told us the engine wouldn't work if it was off. But we suspected this because it ran fine before we took it in to him.

I havent checked the cap and rotor. The car runs very smooth though with no misses or hiccups all through the RPM range.

Is reseting the ECU anything more than unplugged the battery for a while?

Checking fuel was next, we just thought it had to be the timing because after we had the belt changed it ran slower than when we took it in.

Thanks again for the help! It definately reinforces our thought that the timing was off.

Pheonix

It'll still work if it's way off. It simply shifts the powerband around alot.
Check the timing. Set it to top dead center & check the sprockets, or pop the valve covers & check the actual alignment dots themselves.

For the ECU, pull the EFI fuse for a second & put it back. Fuse box nearest the battery.

I think the timing is way off. Pop the valve cover & see. Keep in mind if the rear bank cam timing is off, the entire ECU controlled system is off. The ECU get's it crank & cam position sensor inputs frm the distributor (rear bank), along with the base ignition timing (10*btdc).

If you put the ECU in diagnostic mode (TE1 & E1 in either diagnostic port), the ignition iming should be 10*btdc. If it's not, the rear cams are very likely off. If you set it to 0*btdc on the crankshaft & pop the front valve cover off, the alignment dots should be together.