Acceleration Troubles... - Toyota Nation Forum : Toyota Car and Truck Forums

ac604605 · 05-08-2008, 08:36 AM

I own an 85 MR2 that recently spun a bearing. It now has a rebuilt engine in it that runs fine except for one thing, at around 6,000RPM the engine holds back and will no longer accelerate. If you rev the engine in neutral, or accelerate around quarter throttle, the engine will make it all the way to red line. The old engine didn't have this problem, and we reused parts such as the TVIS, distributer, MAF, and pretty much everything else. All of the obvious spots have been checked: fuel pressure, fuel filter, MAF, throttle position sensor, air filter, spark plugs, timing and the like. Haven't check the pressure regulator or injectors. Figured since the engine was rebuilt they would be alright, but wouldn't rule it out. Any thoughts on this? Since it seems the problem only happens when you're putting a load on the engine, I can't think of any way to re-create the problem when its just sitting in the driveway. Any help would really be appreciated. I've posted the same problem on mr2.com already. Thanks for the help!

tHa kNiGHt FaLL · 05-13-2008, 08:14 PM

if you can rev higher than 6k at idle it eliminates TPS...

i'd go over the vacuum lines first for all the fuel system... make sure they are all connected and connected where they are supposed to be.

then you'd move on to your load sensors... the VAFM... you test the same way as the TPS sensor... w/ a voltmeter it should read .5v closed and 4.5v open....

map sensor is hard to check cause you need to be driving... and have a voltmeter connected... so if you get that far i'd just change it to be sure...

ac604605 · 05-16-2008, 08:36 AM

Thanks for the help. I quit updating the situation here because no one had responded, but I just recently discovered that the TVIS system was FILLED with black sludge, I'm guessing from the clogged cat that I had. Fixed the cat, and did my best to clean out the TVIS however I still haven't taken it off to check and see if the butterfly valves are working properly. I'll check all the fuel vacuum lines today, but I have already checked everthing on the car with a volt and ohm meter, no problems yet.