Bogging past 4k rpm - Toyota Nation Forum : Toyota Car and Truck Forums

rony · 01-03-2005, 12:42 PM

O.k all of my buddies engines sing to 7k rpm... my engine though, hesistates and bucks and just does nothing at around 4k rpm... i have all new ignition components, timing is correct... no boost leaks... no vacume leak that i have been able to find... I really don't know what else to check besides fuel filter which I am going to check in a few days... Any suggestions?

TheMajesticking · 01-03-2005, 01:16 PM

That's exactly what my car was doing recently. I had the plugs and wires replaced and it killed the problem. Are you sure that the parts are good?

Strat42586 · 01-03-2005, 01:19 PM

Yeah, mine has been doing something similar. It will eventually reach around 6k, but it sounds like it will break if I go past that. It takes a lot of time and sounds like it struggles up to that point. I have done the same things you have, including an entire new cooling system and ct26 turbo. Mine only has 59k miles on it, 91 turbo. I just have an intake and boost controller. I have yet to replace the fuel filter as well, so that is on it's way. Just to let you know you aren't alone.

BDSL · 01-03-2005, 01:27 PM

Then check compression.

rony · 01-03-2005, 01:32 PM

Compression came out perfect too... did it not too long ago, nothing too high or too low. As far as ignition I checked everything out as the bgb says to with a multimter and everything turned out ok... I think I'm going to test again right now since I have some free time... double checking never hurt anybody.

JekylandHyde · 01-03-2005, 01:41 PM

Maybe your TVIS is not opening?

You only have 4 intake valves until the TVIS opens, then you get full breathing of 8 valves.

rony · 01-03-2005, 02:19 PM

O.k I checked out my cap wires and rotor, everything is ok... I checked with a multimeter and they were all within specs, ignitor too was within specs... I only had a problem getting a readying from the primary coil... but that was due to my multimeter not fitting... the secondary was exactly between specs...

I really know nothing about testing the TVIS, think yuo can give me some pointers so maybe I can inspect?

teamols · 01-03-2005, 06:19 PM

fuel pressure and flow rate because you maybe running lean, if ok check your boost pressures for lack of contribution.

JekylandHyde · 01-03-2005, 08:47 PM

You will not run a 3SGTE lean with the CT26.

For the TVIS, look here:
http://www.mr2-tech.com/bgb/mechanic...l_052_0001.jpg

Notice it changes right at 4200 rpms. That is why I suspect that it is not opening.

rony · 01-03-2005, 10:32 PM

^ could I use a regular boost gauge to do this? Thanks for the tip, sorry to ask so many questions but do you think you could point me in the direction of a good read concerning the tvis... i've heard much about it but really don't know anything about it as I am fairly new to MR2's (got my first one on August 23rd of last year) Thanks a lot.

JekylandHyde · 01-03-2005, 11:07 PM

All I really know is that around 4200 rpms the second set of valves open up.
I have never played with or tested the system myself.
I merely know that it exists.

There is most likley loads on info on mr2oc.com, but they are crrentyl updating software so they are not online tonight (not sure when they will be back).

rony · 01-03-2005, 11:24 PM

^ ahh thanks for the info man, but the most incredible thing just happened to me (lol, sounds corny but read)

I've been driving the car a little harder then usual since I've been diagnosing lots of things since I have available money to finally fix the car instead of driving it like my grandma. So I finally got around to checking EVERYTHING, and retightening everything... I mean my exhaust, all ignition tested and torqued properly... timing double checked, compression... the works (I had the day off) but earlier today I was still w/e about it, kind of down... I posted on here and on mr2oc.com about my problem... So about 20 min ago I'm on my way home and I hop on the highway to avoid cops in the area... (heading home from my gf's house) and I decided to step on it... I thought the same old thing would happen and boom, next thing I know I sang to 7k no problem!! WTH ;D The problem is completely gone? I have no idea what could have fixed it... since even when I retightened everything I hadn't tried pushing the car... could it have been carbon buildup somewhere? Got magically blown out maybe when I hit 12psi w/ just intake and gutted cat? I'm so happy! Finally after having this car limp around since August everything is OK!! Thanks for all the help guys!!

Strat42586 · 01-04-2005, 06:40 PM

I just had my fuel filter replaced, and my car sings as well. Pretty happy it was something simple. Stupid previous owners.

rony · 01-08-2005, 11:40 PM

Surprisingly it came back, I haven't received the fuel filter from partznet yet...I really hope its just the fuel filter because I'm getting sick of trial and error, gahh!

turbo_GT · 01-09-2005, 02:47 AM

hey rony..i have the exact same problem as you....i was going to post before about it but realized that yours was fixed..but came back...i thought mine was fixed too before..but i was wrong...it can't be the fuel filter...i changed mine and nothing was changed....with the fuel filter...it should be hesitating even when reving at idle...not just when driving...after changing my fuel filter...i noticed that my TPS was lose...that fixed the problem...might wanna check that...only thing is..mine came back after a while..but realized that i had a cracked spark plug wire from the ignition coil to the distributor cap...so i wasn't getting any spark especially at high rpm....i fixed that problem..worked for a while and came back again....another thing i checked was my timing...when i got my engine and first time it ran...my timing was at 30...when i had the problem..we set it back to 10...now it's at 15 and it ran fine for a while but came back again...im planning on setting it up to 20 to see if it would change a thing...but for now....my main concern is voltage....the way my set up is..the maf is right beside the battery..and there's a metal piece that's connected to the + side of the battery and touching the maf causing it to spark andcausing my car to die sometimes...a little electrical solved that problem..but after time..the tape gets ruined...by 4000 rpm...that's where we get most of the torque for the 3sgte causing the maf to move around and create a spark...i dont know if that causes the battery to die....now my last concern is tha maf...this only started happening when it got cold...so i dont know if the maf is opening up properly so for now..im gonna have to wait til it gets warmer...cuz from then i fixed fuel...and spark....only thing now is air.....hopefully you get this fixed and share it with me and everyone else...cuz seems like a lot of people are getting this problem....thanks..sorry for the novel...