Why I'm not a mechanic - UCF11 Wierdness.

[Bendrx]

Hello all, hoping somebody can shine a bit of light on my lastest auto adventure. A few months ago I changed out my timing belt and water pump on my 94 LS400. I didn't do it quite right. Above 4K RPMs it make no power and sounded pretty bad, not rough, just extra loud and not at all "Lexusy". It didn't even have enough power to rev to 4.5K. Also with my MAF unhooked it seemed to run much better. All in all, it ran fine at everyday speeds so due to time I let it be. So fast forward to this weekend. I took off the crank pulley and cover. I marked all the pulleys to the belt. (I bought one on the internet and it has no marks of its own.) Then pulled out the tensioner and slide the belt partially off crank gear. Held the cams in place and with a rather large wrench "jumped" the timing by 1 tooth as I believed that was what was needed. Reassembled and found that I rotated it in the wrong direction. Later that night at perkins I drew it out on a napkin and verified that I had indeed screwed up. So today, I tear it back down and move it 2 teeth the other direction. Started right up as it did when I went the wrong direction, but this time it didn't sound carberated. So all good. I check the timing with a light and it's at about 7 degrees on the guage. Yesterday it was bout 20 degrees. I took it for a quick test drive and it drove fine with the MAF installed. My check engine light that had been on since the first belt adventure was turning off and on (NOT blinking). It seemed that whenever I took my foot off the gas it would turn the Check Engine light back on just a moment later, and when giving it a little gas again the light would turn off. So I parked, finished up reassembly. Plug cover (the passenger side was already on due to the intake) and I also had the batter light blink on for a minute so I resecured the terminals as well. I was working at a friends house so packed up and headed for home. It stalled on 4 occasions when my foot was off the gas. The first was when backing out of his driveway, just as I was about to put it into drive. Then down his street, I was slowing down to for the stop sign and before I ever stopped it was stalled. (Yay, no power brakes). So I sat there for a few minutes "toying with the car" I got it to stall again when shifting from D to N, and then 1 other time when I gave it a nice big rev, the RPMS dropped like they always have or maybe a bit slower but then it kept dropping and hit 0 RPMs. Every stall has been super smooth to the point that I noticed the stall when trying to use the gas pedal (or the one time the brakes). There is no shudder or anything. The rest of the trip home, about 10-15 minutes of stop a go there wasn't any issue at all. For some reason it seems like the car likes to do this and then "fixes itself", though I'm sure it's just compensation for my incompetence. Anyways, I assume that it's done stalling now. So about 5 hours later I get in my car and take a quick drive to grab some food and it smoothly stalls again on me while stopped. I think it wanted to a couple other times but I was watching the tach close and didn't let it. I go to drive through thinking it will be ugly but no more stalls. I came back to my house and just idled while I ate for a few minutes and cranked up the AC to try and stress it out a bit. No stalls. I did find that below 2/2.5K it seems to surge a bit, but still maintaining a smooth feeling - and it pulls nice and smooth with good power to redline. So a few other notes of importance. I had previously been running it with the MAF unhooked as it ran better with the timing as it was before yesterday. Currently I have it hooked back up and haven't tried it off yet. I was/am suspicous that the MAF had gone bad when I changed the timing belt. It is my opinion that a faulty MAF would explain my current issues. In reading around, I had noticed that I had a slight crack in the plastic resonator chamber right where it connects to the TB, but it's small and the rubber gasket should be covering it, I don't feel this is the culprit but I will take a look at it tomarrow after work. I'll also unplug the MAF again and see how it does in the morning. I'm thinking that the stalling thing is only occuring when the engine isn't up to temp yet. So while "toying" with the engine it finished it's warm up (I wasn't looking at this while it was happening, so just a theory.) I hope I haven't confused anyone as there are 3 repair attempts in this. The inital belt change and then the Saturday attempt and the more succesfull Sunday (today attempt). Yet another bit of possibly helpfull info. When I used the timing light after the inital belt change I wasn't getting a consistant reading. The line was jumping between about 2 degrees and then way way off the left, maybe 50-60 degrees. After Saturday it was about 20 and stable, and then today it's stable at 7. I assume that I still need to move the timing 1 more tooth. The 2 teeth took me from ~20 to ~7, then one more should take me to 0 (21 - 14 = 7degrees per tooth) where it belongs. I do fear that the amazingly badass 1UZ-FE is adjusting it's ignition timing to help make up for my lack of skills. Basiclly, any thoughts, or constructive comments (other than stop working on cars, because I never will!!!) would be greatly appreciated. Also, at higher RPMs, can't say what RPM is the turning point, but the Check Engine light turns off still. On my trip to get food I found that the "gas = no light, and no gas = light" relationship had broken down, but it never fully warmed up until I was parked again (short trip). My plan of action for now is as follows:

1) Unplug MAF and ensure there is no air leaking in the small crack, or anywhere else on the intake. I will do this before work tomarrow, and if needed address any leaks after work.

2) Either get a new MAF or see about getting it tested.

3) Once it's more stable and I feel confident it is needed move the belt one more tooth and hope to God I don't have to tear it down again and then move it back

Sorry for the long read, and hopefully it will make sense to you all. My English professor told me I was a "stream of concsious writer" and it's true.

Thank you for you time reading this.
-Ben

 

[Bendrx]

Quick update, decided to take a look at it tonite instead of staying in bed. Disconnected the MAF and no surging issues whatsoever. I only took a quick test drive, the engine was still warm. I did put it into N while driving to give it a nice big rev and it did the smooth stall thing again 1 time. I started it back up with rolling, blip'd the gas and put it back in drive, and it continued right on. Put it back in N and no stall, gave it a nice big rev and it still seems to be happy up top without the MAF. I think this concludes my MAF has issues. The Lexus dealership said that it should read 0 at idle, but it seems to run perfect at it's current ~7 degrees. So on to MAF I suppose. But any thoughts/ideas etc... would still be greatly appreciated.

 

[Bendrx]

Update: Made it to work with no stalls (15-20 minute drive, stop and go). MAF unplugged, ran great. When I put it into park it did stall. Engine was already warmed up at the time. The stall thing still confuses, me, it has good power from top to bottom again, and I don't think it has ever ever ever ever stalled, including with the MAF unplugged previously. Thanks for any input.