Engine does not want to go over 2800rpm

[LMSC400]

Hi all..I'm new here to your forum and have been quite impressed by the members knowledge and feedback given. I hope you can help me as well. I am working on my 92 SC400 and have just completed changing the water pump, timing belt, intake manifold gaskets, spark plugs and wires. I have inspected the distibutor cap and rotors and find them to be OK..no arcing present...but am going to change them as well. The timing belt is aligned currectly as well. The engine started up fine and runs very well at idle. My problem is this..the engine does not want to go over 2800 rpms whether in park or on the road, it begins to feel like it is bogging down. A timing light was used and at idle..800 rpm..shows appr. 7 to 8 degrees, when increasing the rpm, it does advance and at 2800 rpm the timing jumps all over the place including below 0. No check engine light is present and as a check, disconnected one of the cam angle sensor leads to see if check engine light would come on and it did...reconnected and went off. Also, the cat gets very hot.
Before above work..I don't recall having any problems with clogged exhaust or cat.
Thankyou in advance for any suggestions you may all have.

 

[sideshow]

if yr cat gets hot it means the timing is retarted

i would double check the timing as its the only thing u changed that u can really get wrong

i have had customers to do this before idles ok but when u driveit its very sluggish doesnt want to do

timing should be 10 to 12 at idle not 7
so im guessing u have one cam a tooth out as one tooth is around 5 degrees

so just remove the top covers put the crank on top dead and recheck
im pretty sure thats yr prob

timing marks can be out 3 to 5 millimeters and still look ok but theyre not ok so double check

 

[LMSC400]

your diagnostic sounds good and appreciated...as did another mechanic say the same that timing sounds like it's out....I have taken off both cam covers and have manually turned the engine to TDC...both cams are aligned to there respective marks (manufacturer marks) and alignment marks I made prior to removal of timing belt. I agree with your assesment that cams are out since I'm getting firing down the exhaust to heat the cat. Now the question is if both cams are aligned to engine marks....Do I move both cams a tooth and in which direction? or can there be another problem/fix?

 

[Peewee]

Usually if the cams are out one tooth the ecu will throw a code to tell you.

So this all began after you did the work? it was perfect before?
Pull a few plugs out, make sure you are getting spark on all 8, and that all the gaps are good.
These motors are surprisingly smooth at idle with only 4cyl's working.

Its worth a check to see if the cats/exhuast is blocked.
Low exhaust flow will cause the issues you say.

Bridge TE1 and E1 in the diagnostics box, make sure the timing is now on 10
I'm not sure where it is without the bridge wire in, or what it does when you free rev it. I've never tried it, but no doubt its different under load.

 

[sideshow]

these engines run smooth but u still should pic a miss

i can tell if one or two leads are bad

the ecu should thro a code 13 if the timing is out

but it has to be somehting he played with to cause the prob since it wasnt there before

 

[LMSC400]

I believe I have found what was causing my engine to miss. I was in contact with another mechanic and as he is not familiar with lexus engines we could only diagnose generally, anyway he suggested checking the crankshaft sensor for any kind of damage or crud on it. I removed the sensor and was checking the shaft and realized that the TIMING BELT GUIDE (No. 1 Crank Angle Position Plate) was in line with that sensor. I had inadvertantly damaged two of the teeth on that plate and unaware that it was crucial to the timing, just put it back on. Please correct me if I'm wrong, with two of the teeth missing the computer is not advancing without sensing one of those teeth and just keeping the engine at static (2800 rpm) and sounding rough because it does pick up the remaining six teeth.

UPDATE: I was able to order the timing belt guide via a lexus dealer and replaced the old one (missing teeth). THIS SOLVED THE PROBLEM. I would like to thank those whom have given me advice on my problem and wish those whom attempt to change their timing belt the best of luck and it really isn't as hard as some make it out to be, just be carefull of all it's components.