sostahoe

94 truck v6 had 245k on it and 2 cylinders had bad valves (leak down at 0%). Was running good, but a bit rough and the milage was a joke and wouldn't smog. I was offered an 88 4runner that had a low mileage motor installed that was running fine till it developed a loss of power issue and the shop couldn't diagnose it (EFI prob?) big $ estimate to repair, and owner let it go to scrap. I was able to drive it, and it would idle and run smooth, but no power. I did a leakdown test (all 6 holes tested above 75%) and verified the timing belt (was replaced at motor install, and it looked new). So I got it cheap. Did a motor swap using of all parts from the 94 and using only the 88 motor as a long block and intake base. NOW the problem! The replaced motor still has not power. I have verified cam and Ignition timing. The fuel injectors (from 94) were profesionally cleaned and matched. The power level is so bad it cannot get too 3r gear and 30 MPH in a city block. I am at a loss. Anyone got any ideas????

sostahoe

I noticed that the CAT was glowing, very very hot. Bright red from cat all the way back to muffler !!!!! I am quite sure it never did that with the original motor in the 94, but the cat was not connected on the 88. I don't know if it may be because I had tried to clean the intake with carb cleaner ( I know that's a NONO), I was trying to determine if intake may have been overly laden with carbon build up at the intake valves. Maybe the 88 motor was running with a bad EGR ????
UPDATED again see #14

motoriderbc

I'd check the T-belt again, since the problem transfered with the long block. I've seen Toyota's shear the locating pin on the cam gear. The cam gear then rotates out of position compared to the cam, but the timing marks are aligned still. Another possiblity is tight valves.

Before you start ripping it apart, is the timing advancing as rpm increase? Do you have vacuum readings or running compression readings?

jimmyray

cloged cat would def. make it run bad.

My814x4

Agree with the clogged cat , disconnect the exhaust pipe and try it.

thook

Yeah, check the valves. No check engine light?

Would a clogged cat cause it glow red hot?

jimmyray

oooo yeha red hot cat means it is not getting everything out its like having a potato in the exhaust this happend to my chev

sostahoe

there are NO codes. I also have verified with the owner that the 88's power loss problem came on suddenly. That would be the reason I had ruled out valve adjustment.

jimmyray

its the cat!!!!!!!!!

jimmyray

if it is glowing then its ˟˟˟ed up

motoriderbc

If its running rich or misfiring it will overheat the cat as well.

mochester

the cat is definitely a huge part of the problem

if there are other parts to the problem, the clogged cat most likely caused them

i hope you have taken the cat off and aren't driving it around town glowing red hot

your engine can't breathe

thook

Just how did you go about cleaning the intake with the carb cleaner?

sostahoe

I have pulled cam sprockets and verified piston too crank timing and it's all on time. I have pulled cat and replaced with a empty can. Still no power! What the @#%@$#????????? anyone please help.

Yotapup

Did you run truck while cat was off? You stated it was glowing red to al the way to the muffler. Possible blockage past cat.

JamesD

The truck is running super lean that is why the cat is glowing. A richer mixture runs cooler. Toyota 3VZ's are known to have clogged injectors and over a period of time while it slowly runs leaner, it burns vavles. Did you swap your old injector rail on new motor? Also if the timing is way advance it will make it run really lean.

James

motoriderbc

Cat convertors only overheat if too much raw fuel fuel is being dumped into them. Either from running very rich or a misfire. If the engine was running lean there is no hyrdrocarbons(fuel) for the cat to react with to create any extra heat. In fact a lean running engine causes the cat to not light up at all.

A common myth is that a lean running engine runs hotter than an engine that is running at optimum 14.7:1. A rich running engine will run cooler combustion temps because of the cooling effect of the unburnt hydrocarbons.

JamesD

Raw fuel means it didn't burn. Cats glow cause they are lean. The lack of oxygen (rich condition) will make exhaust gases cooler. An excellent example is an EGR valve. It takes burnt gases and recycles them in the intake tract to lower the temperatures in the combustion chamber. Rich condition doesn't cause valves to burn, a lean mixture does.

James

motoriderbc

Sorry, I stand by what I said. You'll never see a lean running engine have a glowing cat, it has to be misfiring(Could be a lean misfire, but now there is unburned fuel going out the exhaust)

EGR systems do lower combustion temperature, by displacing air/fuel charge with inert exhaust gas. The actual air fuel ratio doesn't change. ie it hasn't made it "leaner" or "richer"

DeathCougar

iTrader: (23)

Check your TPS....my 87 Had the very same issue. No power, glowing red cat. Turned out the TPS was bad.