Supra Forums banner

1 - 20 of 28 Posts

·
Registered
Joined
·
606 Posts
Discussion Starter #1
background: did MHG+timing belt etc and ended up not very successful.
Car wont run worth jack if I push it even a little, starts to "stutter" a lot after 3k rpms. The rpm just bounces up and down as the turbo attempts to spool. I can still hear the BOV. My mechanic confidently says he fixed the timing and suggested to me that my turbo might be the reason. He works on imports a lot and told me he just did a MHG job on a mk3 Supra turbo recently, so he seems legit and knowledgeable, plus he's my mom's relative so I doubt he would screw me.
He pointed out this thing, probably the actuator, and said that its not moving normally when the turbo comes in. He said if I looked at the turbo on a working Supra, I would be able to see the actuator or some other turbo component physically move. Is this true? I have never noticed it, I just assumed all movement occured internally. Please comment on this. FYI, the engine and turbo ran fine before I made a smart move to put in a MHG, was able to boost 11psi, stock turbo/bov. Thats the only reason Im confused, because the turbo system was fine before. The OTHER possibility is that some/most of my exhaust manifold threads got stripped off during the process and I half assed putting it together-could this result in exhaust leak to the point where my car runs like total SHIT? I have noticed exhaust gas leaking out at times. I've checked the intercooler piping, from what I see, no leaks or loose fitments. Please help, Im out of ideas. Any other possibilties other than turbo/components, intercooler pipe leak, or exhaust manifold leak? Dont just list things, but things that make sence in my particular case.
 

·
Engine Geek
Joined
·
359 Posts
stuttering in boost could mean a boost leak.... and can also mean ignition problems being poor spark or incorrect timing. did you check the accordion hose for leaks? that can cause a poor air/fule ratio which can do the same thing.

or if your mechanic was pointing out the wasegate actuator it might mean oyu have fuel cut. how much boost do you get before it cuts out?
 

·
Supra hail dent king :(
Joined
·
1,155 Posts
a shitty (going out) fuel injector can also cause stuttering after a few rpms under wot.
 

·
Registered
Joined
·
606 Posts
Discussion Starter #4
i dont think its fuel cut, I can barely boost.
So do you have any suggestions to improve the ignition? Plugs? Wires? Coilpack?
I swear there are no leaks in the intercooler piping, I've looked it over a few times.
To try and narrow things down, does anyone think an exhaust manifold leak can make the turbo/engine run that poorly? Or would an ex mani leak not have that much an effect?
 

·
what would jesus drift?
Joined
·
987 Posts
get some dish soap, and make a solution, and spray your coupler joints, rev it up a few times and look for bubbles, if you dont find any, take it for a quit drive, like 500 feet to boost and get it to do it... then look for bubbles or what not..
 

·
Registered
Joined
·
131 Posts
Exhaust leaks wouldn't cause the problems you describe. Boost leaks could cause what you are describing though. Put together a boost leak tester and pressurize it. Another thing that I'm also guilty of neglecting, besides boostleaks, are engine grounds specifically the one between the upper/lower intake manifold. That one being loose caused my Supra the exact same problems you are describing.:) Good luck.
 

·
Boostin
Joined
·
1,280 Posts
did you already do a leak down test? if not I could borrow Jza71 air compressor and come do a leak down test. Do a 30 PSi leak down test to see if there are any leak near the intake manifold. or the exhaust manifold. 30 PSI should be enough pressure to sqeeze threw the smallest leaks so you can locate the leak. LMK.
 

·
This Is Why I'm Hot.....
Joined
·
1,984 Posts
Supra_Dre said:
where are all the damn experts
Can faulty spark plugs do this much to performance? How about wires?
Telling the Internet your car stutters is not much to go on. Doing major engine work & having a problem usually means something was either damaged or installed improperly. Instead of whining, go over every component/sub-system that was touched. Take it apart, inspect, & re-assemble if you have to.

You yourself said there's an exhaust leak. If the manifold is loose, fix it. It's likely not the primary cause of your issue, but it definitely compounds diagnosing the root cause. Make sure all the vac hoses are on right, & that all elec connections are secure & proper. Hell, I could go on all day, but I'm going to go for a top-off drive on this beautiful sunny day.

Good luck.
 

·
Registered
Joined
·
606 Posts
Discussion Starter #13
OK, so i've narrowed down my possibilities a little:
*exh manifold leak-->stipped threads, loose bolts. Yes, its loose, but can it cause to the point of no power/driveability.
*boost leak from intercooler pipes (but I cant see any, Im no expert but I've checked and re-tightened them many times)
*bad ground. I am the idiot newbie that grounded the wires, so that could be the problem and I've gotten some responses that bad grounds can do this.
So can someone take me through the steps of checking the "main" grounds? I know there's the big one on the intake manifold and one on the exh side by the firewall. Also, pics of them would be great.
 

·
Registered
Joined
·
606 Posts
Discussion Starter #14
yes it runs fine until higher rpms
So i'll try replacing the intercooler hoses as my next step
 

·
Registered
Joined
·
231 Posts
read the PM i wrote you. use start-gas... its called diesel start here in denmark, when the engine is not under boost it is actually a normal suction engine. When it sucks in the start-gas it will raise the RPM abit. Use that to localize boost leaks. And remember, there might be more than one leak! You car does exactly what mine did untill the leak became so big that i hit fuel-cut.

Michael
 

·
Registered
Joined
·
606 Posts
Discussion Starter #16
ok so since its "sucking in" then run the gas around the intake and intercooler then? Start gas? Should I be able to find it at an autostore or should I go to a bigger hardware store? Will do it tomorrow.
 

·
Registered
Joined
·
231 Posts
In denmark its called Diesel start or start gas... I guess you guys call it "ether" its an excelent tool to find leaks with.
And yes its sucking it in, thats why you have vacuum :) Just dont spray too much in the hole ;)

Spray it on all the intake hoses, intercooler, between the runners on the 3000 pipe.

The hose isnt really that hard to get to, just take of the hose going from the turbo to afm and you can get a socketwrench in there. that is if the hoseclamps is turned corretly :)
You can get to the other end from below, you have to remove the little metal pipe that sits between the hose in question and the intercooler hose. Took me around 15 minuttes to do. Really isnt that hard :)

It might also be a small crack somewhere in a hose that when not under boost is insignificant. When the boost comes the hose expands and the air flows out. Can be alot of things. Also check all the vacuum hoses.


Michael
 

·
Boostin
Joined
·
1,280 Posts
DeanMarcum said:
Um, there should not be any vacuum in the intercooler piping system. Only after the throttle plate is there any real measureable vacuum. Just pull off the intercooler hoses and bend them around to see if there are any cracks. My best is that it is the hose coming off of the turbo, yes, the hardest one to get to.

that what we are going to do tomorrow. I going to bring mines over and see if it work.
 

·
Registered
Joined
·
606 Posts
Discussion Starter #20
timing should be good, mechanic adjusted it and sounded very confident that it was correct.
 
1 - 20 of 28 Posts
Top