89Steve Posted February 11, 2009 Report Share Posted February 11, 2009 So the other week I was driving to work when I noticed the car started bucking on me. I figured great this is the first time I've ever let the fuel run this low I probably clogged a filter. So the next week was spent cleaning out the tank (which looked near spotless), replacing all fuel filters (except high pressure one...replaced that in june), and even put in a new fuel pump I had sitting around. Also hooked up a pressure gauge. Well, I started the car up after the job was done. Pressure read 40psi and it was idling fine except for a hiccup every so often. Took it out for a drive and it was still bucking under any sort of load. It can actually boost fine, the turbo can spool but it just jumps the entire time. Its not a matter of what RPM i'm at cause in first gear I can rev to 4-5k just fine. It's when I go to a higher gear (does it in 2nd sometimes) and running at low RPM then when i lay into the throttle a bit it just hiccups and bucks pretty hard. Any excessive load does this. So here's what I've checked so far. -Fuel -- obviosuly I replaced the pump and filters and have good pressure -Replacd both injectors with known working ones. Pigtails are brand new. -No ECI error codes from checker -Plugs are NGK gapped at .040 My problem is I feel like it's ignition but honestly am not sure at all. That's just a gut feeling. If anyone has ANY advice that I should try any input is much appreciated. Oh and here's a little history about the Starion: -Pearl White 1989 Starion -Engine, TB, Cooling System all rebuilt/cleaned up in june. Car was basically stripped down then put back together. -Trying to get it to run perfect stock before I go for any big upgrades. Although I do have a nice new 19c sitting in my room. RECENT work done (right before problem started happening) -Distributor rebuilt (VAC advance works perfect) -TPS replaced with known working one (calibrated) Thanks in advance for the advice -Steve Link to comment Share on other sites More sharing options...
89Steve Posted February 11, 2009 Author Report Share Posted February 11, 2009 just to add to this... I popped in a new ECU so all error codes were definitely gone. Came to find that the MAS code was popping up. Looks like a had a nice slit in my boot right by the turbo inlet. Could this have caused the bucking? I don't really see how it could affect it that much, but then again i only know the basics on this setup. Any ideas? Link to comment Share on other sites More sharing options...
Hoosierquest Posted February 11, 2009 Report Share Posted February 11, 2009 (edited) yep, you need to get a new accordian hose (airfilter to turbo inlet). if that is split it is probably letting unmetered air enter anytime the turbo starts to really move some air. You can get a hard pipe there for nearly as much as it cost for the stock accodian. The Ecu uses the mas to meter the amout of air being supplied to the engine. If you have air entering after the mas you are going to have problems . Edited February 11, 2009 by Hoosierquest Link to comment Share on other sites More sharing options...
Technology Posted February 11, 2009 Report Share Posted February 11, 2009 Yeah, and you can clear codes by unplugging the battery. ignition problems don't make the car buck. too much air and not enough fuel does it. a fuel cut from the computer or some major air leak somewhere, or bad injectors. I've installed "known good" injectors and they weren't perfect. Better than bad ones, but noticably not perfect. Link to comment Share on other sites More sharing options...
89Steve Posted February 12, 2009 Author Report Share Posted February 12, 2009 so today I sealed up the accordian boot (temporarily with lots o duct tape) and tried it out. It now boosts better but still bucks. I noticed by UNHOOKED 1g BOV was sounding off whenever I shifted. The thing leaks like a mother when it is hooked up but now its leaking when its not? So I took off my OVCP and replaced the stock piping. STILL bucking. No other air leaks I can possibly come up with. I'm stuck for now. Link to comment Share on other sites More sharing options...
Wizard Posted February 12, 2009 Report Share Posted February 12, 2009 so today I sealed up the accordian boot (temporarily with lots o duct tape) and tried it out. It now boosts better but still bucks. I noticed by UNHOOKED 1g BOV was sounding off whenever I shifted. The thing leaks like a mother when it is hooked up but now its leaking when its not? So I took off my OVCP and replaced the stock piping. STILL bucking. No other air leaks I can possibly come up with. I'm stuck for now. How old are your spark plug wires? When was last time replaced? Cap, rotor? Vacuum tubing hooked up correctly like diagram under the hood? Wizard Link to comment Share on other sites More sharing options...
89Steve Posted February 12, 2009 Author Report Share Posted February 12, 2009 How old are your spark plug wires? When was last time replaced? Cap, rotor? Vacuum tubing hooked up correctly like diagram under the hood? Wizard Plugs and wires were all replaced this past summer. Cap and rotor replaced about a month ago. Vaccum lines were all double checked. It was running great for about 3 months until it randomly started to buck. Link to comment Share on other sites More sharing options...
Wizard Posted February 12, 2009 Report Share Posted February 12, 2009 Plugs and wires were all replaced this past summer. Cap and rotor replaced about a month ago. Vaccum lines were all double checked. It was running great for about 3 months until it randomly started to buck. How bout coil? How old is that? Other than that, sounds like some type of fuel transition problem between the primary and secondary injector when it is kicking in. Wizard Link to comment Share on other sites More sharing options...
89Steve Posted February 12, 2009 Author Report Share Posted February 12, 2009 coil is still original but resistance tests all passed. could it not be getting enough spark? And even if its not Technology posted: ignition problems don't make the car buck. too much air and not enough fuel does it. like i said i know all the basics on these cars but no where close to everything. thanks for all the help Link to comment Share on other sites More sharing options...
ESTurbo4 Posted February 12, 2009 Report Share Posted February 12, 2009 BOV's will leak under boost when they are unhooked. The springs in them are light and when pressure acts upon it, they will release. Many BOV's will also leak at idle because at idle there is a lot of vacuum holding open the diaphragm. That is why many manufacturers use bypass valves that reroute the air escaping through it back into the low pressure side of the turbo. A BOV that is properly hooked up should not leak under boost because when your intake is at 12psi then so is the BOV's diaphragm (via pressure coming through its vacuum hose) and because the BOV has a spring it has the advantage to keep it closed until vacuum is applied. If you have a valve from an Eclipse then that's a bypass valve. The springs tend to be a bit lighter in bypass valves than BOV's so it will most likely leak at idle. For your bucking even though you have a rebuilt dist check your mechanical advance. Take off the dist cap turn the rotor and see if the advance operates freely, if it feels even a little sticky, clean it. Also even though the vac advance maybe holding vacuum and pressure it may not be actually moving the stator, verify that it operating it as necessary. Link to comment Share on other sites More sharing options...
JustPaus_88TSi Posted February 12, 2009 Report Share Posted February 12, 2009 Was the 1G BOV modded? There's a vac/boost port next to the valve face that should be plugged, and the tophat should be "crushed" until you match your idle vac levels to the amount of vac it takes to open it. Link to comment Share on other sites More sharing options...
89Steve Posted February 12, 2009 Author Report Share Posted February 12, 2009 Was the 1G BOV modded? There's a vac/boost port next to the valve face that should be plugged, and the tophat should be "crushed" until you match your idle vac levels to the amount of vac it takes to open it. The problem is, I took off the OVCP and replaced it with stock piping. The car STILL bucks. For your bucking even though you have a rebuilt dist check your mechanical advance. Take off the dist cap turn the rotor and see if the advance operates freely, if it feels even a little sticky, clean it. Also even though the vac advance maybe holding vacuum and pressure it may not be actually moving the stator, verify that it operating it as necessary. Yesterday I unhooked the vac advance line and reved the engine up to verify mech weights were working properly. Timing retarded smoothly as engine revved up. I then rehooked up the line and timing retarded even faster as engine revved up. This is normal correct? It wasn't under any boost so it shouldve done just the opposite of advancing, right? Link to comment Share on other sites More sharing options...
Hoosierquest Posted February 12, 2009 Report Share Posted February 12, 2009 are you still gettting the MAS code? Link to comment Share on other sites More sharing options...
ernielist Posted February 12, 2009 Report Share Posted February 12, 2009 coil is still original but resistance tests all passed. could it not be getting enough spark? And even if its not Technology posted: like i said i know all the basics on these cars but no where close to everything. thanks for all the help Its not bucking at all in 1st gear? Link to comment Share on other sites More sharing options...
89Steve Posted February 12, 2009 Author Report Share Posted February 12, 2009 Its not bucking at all in 1st gear? Nope, i think its cause its not under that much load. And I havent had time to check out the MAS code again. I guess it could very well be my sensor. Link to comment Share on other sites More sharing options...
89Steve Posted February 15, 2009 Author Report Share Posted February 15, 2009 Today I re gapped my plugs to .034, put in Dad's jet valve eliminator bolts, and put an a** load of duct tape around the boot-turbo inlet. Well, no more bucking problem. Looks like I just need a nice accordian boot. Lucky for me BOHO has one on its way for me. Thanks for all the help guys. And just goes to show what a little air leak can do to these cars. Link to comment Share on other sites More sharing options...
ernielist Posted February 17, 2009 Report Share Posted February 17, 2009 Nope, i think its cause its not under that much load. And I havent had time to check out the MAS code again. I guess it could very well be my sensor. Yes the MAS could very well be making the problem. Link to comment Share on other sites More sharing options...
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