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6g74 dohc gen 2 - sudden power loss at 4krpm now no power #1078337 06/23/15 03:45 AM
Joined: Mar 2015
Posts: 14
6
6G74_SR Offline OP
Need a Spot
whats up guys im having a bit of an issue.

last night at 65F degrees about 2000 meters elevation i was driving and went to pass a car and floored it WOT and at around high 4k rpm the car suddenly lost all power and felt like an experience of when you miss a gear in a manual car.

at first i thought it was a transmission issue but noticed it was still shifting fine except it was sluggish as hell. no smoke no noise, was able to drive home but couldn't even keep up with traffic. at idle it sounds like a tractor barely stays on idling roughly 500rpm.

what can it be? spark plug, wires, coil pack , sensors?


95 Montero SR - center/rear locker, Modified 6G74(200rwhp),Stock suspension, white with gloss black trim!

07 FJ Cruiser - rear locker, all stock!
Re: 6g74 dohc gen 2 - sudden power loss at 4krpm now no power [Re: 6G74_SR] #1078338 06/24/15 04:43 PM
Joined: Feb 2005
Posts: 1,511
ryany Offline
Body Damage is Cool
Because of it hapenning suddenly like you describe, I'd suspect something like the timing belt slipping, or one of the variable intake throttle plates came loose and was swallowed by the engine. What is the timing belt and tensioner history on the vehicle and have you ever inspected the lower intake butterflys?


95 Montero SR
3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes
Re: 6g74 dohc gen 2 - sudden power loss at 4krpm now no power [Re: ryany] #1078339 06/25/15 04:52 AM
Joined: Mar 2015
Posts: 14
6
6G74_SR Offline OP
Need a Spot
Problem Solved!! luckily it wasn't all that, i had thought about it at first but the motor was built only almost 8k ago (butterfly valve and new timing built along with the rest of the build)

i bought some quality grade contact cleaner and went ahead and polished the battery terminals, the ground contact cable

then went ahead and removed all fuses sprayed some cleaner, removed every electrical sensors above the intake manifold cleaned them, removed all three coil packs cleaned that aswell as the spark plug wire terminals

lastly removed the intake, deeply cleaned the mass air flow, throttle body, IAC and attached sensors.

put everything together and this baby started back up 100% normal. actually idles more steady a bit higher than before 900rpm with no shutters. drove a couple of miles and drove great tomorrow ill hit the highway and find out forsure.

i believe it was due to a loose connection to a coil or dirty MAF, thanks for the advice anyways

Last edited by 6G74_SR; 06/25/15 04:56 AM.

95 Montero SR - center/rear locker, Modified 6G74(200rwhp),Stock suspension, white with gloss black trim!

07 FJ Cruiser - rear locker, all stock!
Re: 6g74 dohc gen 2 - sudden power loss at 4krpm now no power [Re: 6G74_SR] #1078340 06/25/15 07:28 PM
Joined: Mar 2015
Posts: 14
6
6G74_SR Offline OP
Need a Spot
bad news woke up to the same issue now idling bad again, i begin to suspect bad IAC valve i will check up on it now


95 Montero SR - center/rear locker, Modified 6G74(200rwhp),Stock suspension, white with gloss black trim!

07 FJ Cruiser - rear locker, all stock!
Re: 6g74 dohc gen 2 - sudden power loss at 4krpm now no power [Re: 6G74_SR] #1078341 06/25/15 09:05 PM
Joined: Feb 2005
Posts: 1,511
ryany Offline
Body Damage is Cool
An IAC valve won't effect anything other than idling conditions.


95 Montero SR
3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes
Re: 6g74 dohc gen 2 - sudden power loss at 4krpm now no power [Re: ryany] #1078342 07/08/15 11:30 PM
Joined: Mar 2015
Posts: 14
6
6G74_SR Offline OP
Need a Spot
i was under the impression that a faulty motor on the IACV would cause it to malfunction and not retract causing the engine to not run properly in any RPM.


95 Montero SR - center/rear locker, Modified 6G74(200rwhp),Stock suspension, white with gloss black trim!

07 FJ Cruiser - rear locker, all stock!
Re: 6g74 dohc gen 2 - sudden power loss at 4krpm now no power [Re: 6G74_SR] #1078343 07/09/15 02:37 AM
Joined: Feb 2005
Posts: 1,511
ryany Offline
Body Damage is Cool
I don't think the IAC valve can let any unmetered air into the engine, so it shouldn't have any effect on normal running conditions. Even if it is unmetered air, the amount the IAC valve is capable of allowing in shouldn't have anywhere near the effect on the engine that you're experiencing.


95 Montero SR
3.8 MIVEC, Advance headers, 2 1/2" exhaust, Magnaflow muffler, OME shocks & rear springs, 2" body lift, 3" tank lift, 4.90s, TRE front locker, factory rear locker, Roger Brown Rock Sliderz, 315/75r16 (35") tires, Sport big brakes







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