rionlane

So, the other day I was driving along fine when I came to a stop light, take off as normal and my car instantly bogged down and would not accelerate as normal.I got it back home (1/2 mile away) and put it in park .
It idles a little rough but the biggest thing is that (in park) when I step on the gas it goes up to 3000rom and then automatically drops down to around (fluctuating) 2000rpm.
While driving it, it crawls up to speed VERY slowly.
I took it down the street to have a car shop look at it and the guy took it around the block. He said that he was 90% sure it was the catalytic converter.

Since I only paid $1500 for it and it has body damage I don't want to sink TOO much into getting running (already put $2000 into it).

This is on a 1992 Lexus SC400 4.0L 1UZ-FE (Stock)
So here are the symptoms:
-Loss of Power/ Slow acceleration
-gas smell from exhaust on both ends
-exhaust pipe directly after catalytic converter on passenger side reaches almost 300F (catalytic converter ~ 170F at normal operating temp)
-engine does not overheat

So here is what I have done after the problem happened:
-check ALL fluid levels (they are good)
-replaced ALL spark plugs and wires
-sprayed bolt loosener on back bolts of the catalytic converter that was over heating near pipe
-Put up on stands to get under the car
-Checked the temperature of the entire exhaust system running from manifolds to tail pipe

I have looked and it seems like it is a pretty hard job to get those catalytic converters off.
Any help would be appreciated

blk&blu*j

iTrader: (1)

Welcome !!!!

It helps if we know what engine you have?

rionlane

This is on a 1992 Lexus SC400 4.0L 1UZ-FE (Stock)

Joey-E

iTrader: (1)

Check your ignition coils, there are 2 of them. Common problem overtime.

rionlane

how would I go about checking the coils?

SC400slide

iTrader: (11)

Also might wanna look into o2 sensors. No CEL? If the cats don't get red hot, that means there is no unburned fuel getting into the exhaust which is good. Also might be TPS...but there are many things it could possibly be.

rionlane

No CEL as of yet. Even though I did it a year ago, I will be cleaning the MAF and IACV tomorrow. But it is struggling to accelerate more than just a little. And it absolutely will not go over 3000rpm....

rionlane

is there a way to test the O2 sensors?

SC400slide

iTrader: (11)

Not that I know of. o2 sensors go out so often, with problems like this, I just replace them.

But it seems like Joey-E is on the right track. Ignition coils: https://www.clublexus.com/forums/per...-of-power.html
GL

Joey-E

iTrader: (1)

Id start with your drivers side coil located right above your AC compressor and few inches left of your oil dipstick, unplug it and try starting your car if your notice no change at all and still loss of power it might be it. You could or should also check the passanger side coil which is to the left of the thermostat do the same thing and see if you notice any change at all.

Try using the search function its been covered before.

rionlane

Ok thanks! I will check tomorrow and update on to how things turned out.

rionlane

Well, I took the cable off of the driver's side ignition coil and started it. It ran just like it did before.
Then to test it, I took the other side off and plugged the driver's side back in and it wouldn't turn over at all!

So it looks like I'm off to the store to grab an ignition coil. Will update when I get it installed.

rionlane

+++++++SOLVED++++++++

That did the trick! The little screws that hold the coil onto the bracket were a little rough to get off but the car now runs better than it did before the problem. Thanks to everyone who guided me in the right direction!

Joey-E

iTrader: (1)

Glad you got it solved