2G Loss of power when throttle is open

[jtornatore00]

I got a 97 Eclipse Spyder GS-T that I just freshly rebuilt. It's got a 16g turbo in it and before it was rebuilt it was running fine according to the previous owner.

I've done a boost leak test and can't find any thing too major. I know the throttle body leaks. But no matter how I tweak my boost setup, my car reacts the same way. if you push the throttle too far, it will immediately lose power and the external wastegate will open up and pop real loud shooting a flame . In order to drive it you have to feather the throttle.

Would a boost leak be causing it to do that?

 

[DSMPT]

In order to drive it you have to feather the throttle. Would a boost leak be causing it to do that?

Yes, especially if you are running a MAF sensor. But still one of possibilities. I would also check all sensors and wiring, too. Like TPS etc. If you have a method to log, should upload it.

 

[steve]

Lets see under the hood. There is enough in your profile and your problem description that make be suspect several problems that might be going on here.

 

[jtornatore00]

I know this is quite a bit later, but we have checked all the sensors and wiring. There is a few plugs in the rear driver side of the engine bay but I believe it's for the A/C since it was taken out. We also replaced spark plugs. It sounds like it falls on its face because it's getting flooded with fuel. But with boost leaks sealed up I'm not sure what else to look at.

 

[pauleyman]

I know this is quite a bit later, but we have checked all the sensors and wiring. There is a few plugs in the rear driver side of the engine bay but I believe it's for the A/C since it was taken out. We also replaced spark plugs. It sounds like it falls on its face because it's getting flooded with fuel. But with boost leaks sealed up I'm not sure what else to look at.

Again please post a picture so we can have a look.

 

[waltah]

In addition to pix tell us about the ignition parts. An engine that craps out at full power is often a high voltage failure. Voltages go up, of course, as the pressure in the cylinders increases and the more boost you can run, the bigger this issue becomes. Any part of the ignition system can break down.

What spark plug gap are you running? As a generality the more the maximum boost the smaller the gap has to be but I'd have no idea what would be correct for the pressures a 16g could deliver. And there are other factors that would need the opinion of someone experienced with running higher power -- mine's a stock '95 GS-T.

 

[CptYumyPants]

Would a boost leak be causing it to do that?

yes a leak can, cause it is confusing the computer as to how much air the engine is actually receiving

any engine codes?

 

[jtornatore00]

yes a leak can, cause it is confusing the computer as to how much air the engine is actually receiving

any engine codes?

I can get pictures this weekend, but I know for sure the computer threw a misfire code. But my buddies and I cannot audibly detect a miss.

It's also difficult to detect if it does or not because it has a ghost cam tune.

What spark plug gap are you running?

We swapped with new spark plugs to see a difference but I could not tell you what they are gapped to at this time. We also triple checked timing to see if we were off.

Our external wastegate is being controlled by a manual boost controller, though it does not make a difference with this issue. Boost will struggle to climb past 2 psi no matter what the controller is set at.

 

[pauleyman]

I got a 97 Eclipse Spyder GS-T that I just freshly rebuilt. It's got a 16g turbo in it and before it was rebuilt it was running fine according to the previous owner.

I've done a boost leak test and can't find any thing too major. I know the throttle body leaks. But no matter how I tweak my boost setup, my car reacts the same way. if you push the throttle too far, it will immediately lose power and the external wastegate will open up and pop real loud shooting a flame . In order to drive it you have to feather the throttle.

Would a boost leak be causing it to do that?

Wastegate can't open if you're only at 2psi. It's a positive pressure totally mechanical setup.
Something else is wrong. Where are you boost leak testing? From the turbo inlet? I know you said you checked but everything you are stating sounds like a leak.
What on earth is a ghost cam tune?

 

[jtornatore00]

Wastegate can't open if you're only at 2psi. It's a positive pressure totally mechanical setup.
Something else is wrong. Where are you boost leak testing? From the turbo inlet? I know you said you checked but everything you are stating sounds like a leak.
What on earth is a ghost cam tune?

I don't know why the waste gate would open but when you give it any throttle it'll pop like it has two-step and the flames seem to be coming from the wastegate... I'll post a video when I can get one. We did do a boost leak test from the turbo inlet. A ghost cam tune is a tune that affects the idle. It makes it sound choppy and like it has big cams when it doesn't. I'll attach a video of that.

You must be logged in to view this image or video.

 

[CptYumyPants]

that very much sounds like what i went through just last week
have you by chance messed with/ tested the Ignition Control Module or replaced it by chance?
replaced mine and P0300 code cleared
and all i was left with was my P0100 and cleared that with a new MAF sensor
then the car ran like a champ

shooting another theory at you (based off the hell i went through last week)

is it by chance only running off 2 cylinders?
(unplug an injector from either cylinders 1/4 or 2/3 and see if it dies on both)

 

[waltah]

I would still look for an ignition failure under boost, that is, when the ignition voltages are highest. Plug wires are a frequent failure but any part in the system can do it -- coil(s), transistor, even plugs.

The plug gap matters because it limits how high the voltage can go. Higher boost means higher maximum voltages but if you set the gap smaller that keeps the voltages down. Running too big a gap for the amount of boost puts more stress on the ignition parts and they may fail. And generally once a part fails it will do so again and over time, it will get worse -- even to the point where the car won't start.

Both things have to be checked: Ignition components for failures -- I would start by just replacing the wires and plugs. And plug gaps -- ideally get a recommendation from someone who runs the same boost you do. The gap for a stock GS-T (11 PSI) is 0.028-0.031.

I've fixed two "won't pull worth crap" cars in the last year by throwing away a set of plug wires and installing new OEM. On the ones from the GS-T I was able to see the tiny black dot where it was sparking to a bolt on the valve cover.

 

[jtornatore00]

I will regap my plugs when I get the chance this weekend.

I will also note that when I hooked up an OBD scanner it popped up with a misfire code. I will try to chase that code and see if it moves cylinders this weekend either because of the injector or coilpack.

I will also note that my alternator had a bad pulley on it and we were positive it wasn't charging correctly. We took it in to get rebuilt and when we got it back and installed it, we found out it was only charging to around 12.5v and the car was still behaving the same way.

Still falling on its face with any throttle, barely able to get to 2 psi. I hot tested all of the fuses and relays. I cannot figure out if my regulator is not kicking on or maybe an ignition relay is not functioning. I figure that a component with low voltage could be the root of my issue but I will still try to chase the miss and see what comes up.

I've been told it would be worth to replace my ignition starter switch, but I wanted to knock out the other possibilities before buying a non refundable part.

 

[waltah]

Low voltage can cause all sorts of problems but it's easy to check out. When the car is fully cooled open the hood, start the engine, and promptly check the battery voltage: it should be very close to 14.5 volts. If it is, the alternator is probably just fine.

Additional checks: When on the road at night (headlights are on, of course) and driving least 40 MPH, turn on the heater blower to full speed. Do the headlights dim much at all? There should be little to no change.

When you come back from a drive in the daytime, turn off the ignition and check the battery voltage: It should be at or over 12 volts.

Does the car crank at what you consider a normal rate when cold? The group 86 battery is small for the size of the engine so it doesn't crank as fast as other models but it should be 'slower than some cars' not 'barely turns it over at all.'

If you get a pass on these four tests, don't worry about the battery/charging system -- it is fine.

Most or all Mitsubishi 1G cars had a weak ignition switch. After 100k miles or so the contact for the 'START' position would be burned away to where it would only make contact sometimes. At first you could try a couple-three times and get going but eventually it might get to 10 times or maybe not even then. They completely redesigned the switch; some models got the new switch in '94, others -- Eclipse and Talon I think -- not until the next year. The new switch won't have that problem in less than 250k miles; unfortunately in the Expo/LRV (cars I know best) the new switch doesn't interchange. But a new old-style switch will last another 100k miles.

I've never had an ignition switch failure that didn't show up at the time of starting the car. Never say 'never' but -- not common.

If you narrow the gaps on your plugs significantly to get down to what's recommended for your max boost then if the problem is an ignition part breakdown it will get better. That is your key piece of data. Of course if the problem is completely gone you can forget it, but what's more likely is you can hit higher boost levels but still have trouble. Now you start figuring out which part is failing: The switching around you're talking about will give useful data. Or you could just throw a new set of plug wires at it -- they seem to be the weakest link in that system and high-boost engines are high stress for ignition so new wires are hardly a wasteful purchase.

Good luck with it!

 

[CptYumyPants]

I will regap my plugs when I get the chance this weekend. I will also note that when I hooked up an OBD scanner it popped up with a misfire code. I will try to chase that code and see if it moves cylinders this weekend either because of the injector or coilpack. I will also note that my alternator had a bad pulley on it and we were positive it wasn't charging correctly. We took it in to get rebuilt and when we got it back and installed it, we found out it was only charging to around 12.5v and the car was still behaving the same way. Still falling on its face with any throttle, barely able to get to 2 psi. I hot tested all of the fuses and relays. I cannot figure out if my regulator is not kicking on or maybe an ignition relay is not functioning. I figure that a component with low voltage could be the root of my issue but I will still try to chase the miss and see what comes up. I've been told it would be worth to replace my ignition starter switch, but I wanted to knock out the other possibilities before buying a non refundable part.

on a serious note, test that ignition control module too before replacing coil packs

 

[jtornatore00]

I've gotten the alternator rebuilt over the past couple weeks to where I am getting proper voltage.

We took the car out for quite a drive to study this issue more. In totality we think the issue is there is too much fuel to ignite. When driving, if you push throttle in the slightest too much, the car will bog and start shooting flames. When the car is sufficiently warmed up, it'll be 5x worse.

When the engine detects any sort of load, for example when we come to the slightest incline on the road, the engine will want to stop running completely - though it never stalls. Periodically, pushing the gas will not do anything and it'll make this fast sputtering noise and not rev past 2k and provide no power whatsoever making it nearly undriveable on hills.

The fuel pump in this car is louder than the motor. This fuel pump was installed by the previous owner. The previous owner did mount a fuel pressure regulator, but he did not hook it up. We installed it yesterday and the car still remains with the same issue - even after adjusting the regulator.

We have also messed with the gap in the spark plugs and nothing changed. We have also changed the maf and throttle position sensor along with the icm. Our next thing to try was hotter spark plugs.

 

[steve]

I think you're shotgunning parts.
Based on this frame from your video and the lack of other useful data I have a couple of suggestions.

You must be logged in to view this image or video.

First, make sure your not venting the BOV to ATM and get rid of the valve cover breather. It should be routed to the intake pre-turbo.
Second, get the spark plug wires that are the correct size and length for a 2G.
Third, get rid it this "ghost cam tune" and while you at it tell us what your tuning with.
Fourth, get a current compression test.
Fifth, have someone check the external waste gate for correct operation.

 

[TSiAWD666]

In my experience the two things that come to mind for causes for losing power after opening throttle are:
- TPS isn't working right (in my case the plug kept working its way loose while driving, solution was adding a drop of RTV whenever I plug it in)
- Coolant Temp Sensor is disconnected, the larger one in the thermostat housing (solution was fixing the wiring as it had weakened and broken right at the harness, requiring depinning and splicing in a new wire)

 

[DSMPT]

when you give it any throttle it'll pop like it has two-step and the flames seem to be coming from the wastegate

Also check the mechanical timing. Maybe your valve timing is not set properly.

 

[CptYumyPants]

Still got the Misfire code?
what other codes?