batmanfc

Just got my motor put in. The car runs ok. I believe it still has a vac leak I haven't fixed yet but I don't think it is causing this. Whenever it gets into boost it misses bad. Pulls the best in first and second gear but still misses some. 3rd 4th and 5th are horrible especially up hill it almost dies. In 3rd 4th and 5th the miss isn't nearly as bad if its not under boost and it seems to have a little more power out of boost. Kind of thought that may be a MAF going bad? Also when under boost you can hear a noise that almost sounds like a pebble bouncing around in the intake. Its not real loud but noticable. It idles on its own but fluctuates between 750 rpm and 1000 rpm. It also takes it a few trys to crank. It will crank everytime you try but won't run and hold idle until the about the 3rd try sometimes a few more. Not exctly sure what it is. Thought I would ask and see and listed all these problems to see if it may all come back to one thing. I may still have a few vac leaks that I have to fix too. Don't know if that would cause all of that?

KhanArtisT

iTrader: (2)

Ignition timing.

2slow4stock

iTrader: (18)

+1 ^^

batmanfc

How would i set it?

fc3s91

iTrader: (23)

Check your plugs. If the gap is out of spec it will misfire.
Thanks Robert

batmanfc

The plugs don't gap. Its not like a plug miss its a lot worse than that. Checked the plugs last night too and they seemed ok. Would a leaky injector cause this problem?

Turbonut

iTrader: (1)

Cracked seal?

batmanfc

What kind of seal? Haha I want to narrow it down so I can check it

batmanfc

Would a clogged fuel filter or bad fuel pump cause it? Maybe an oxygen sensor? I keep thniking of things in my head to ask?

calpatriot

oxygen sensor is not in the loop during high-power acceleration.

1. Fix the vacuum leak
2. Pull codes
3. Verify closed loop operation
4. Verify injector operation sounds on the primaries at low rpm, and on the secondaries above 3800
5. Adjust idle speed, mixture and the TPS per the FSM
6. verify proper timing and advance per the FSM
7. Check the EGR, port air, split air operation per FSM
8. Check that the aux ports are opening per FSM
9. Check the boost sensor, air pressure sensor, and air flow sensor per FSM

KhanArtisT

iTrader: (2)

^That list is useless. Vacuum leak wouldn't cause it, closed loop doesn't matter, injectors can't be stethescoped since they're under the intake, setting idle is random, you can disconnect the solenoids if you suspect those in #7 (unlikely anyway), the car DOESN'T have aux ports, and the MAP/air pressure sensor (same thing) and AFM are very unlikely to go bad. I have never heard of anyone having a bad AFM on here, but a lot of people still suspect them since it is easy to change.

lol @ plug gap. I don't think a leaky injector would not cause this issue but you can check them if you want. It is probably ignition timing, you can search up the procedure to set it or follow the FSM.

O2 can't cause it, bad fuel pump is very unlikely and so is a clogged fuel filter.

batmanfc

Thanks man. That gives me a lot more definete answer. What is the FSM? Is that like Haynes manual? If so I have one just curious. I bought one the other day figured it would be very useful and I found the timing procedure. The yellow mark on the crank pulley is L1 but I'm colorblind haha so is that the 1st mark that comes around? I'm going to set it in the morning as soon as I get up. Also, what would cause the rattling noise I was talking about? It only does it under boost and just sounds kind of like a rattling in the upper intake manifold.

KhanArtisT

iTrader: (2)

haha...bro that rattling noise is your engine detonating, I bet it sounds like marbles in a can. I'm not sure if its the first mark, I can check that for you tomorrow if you want though. Set TDC, remove CAS cover, align marks on the gear while noting the position of the pointer and sensor on the top, install CAS making sure the gear doesn't move and it should be set pretty close to spec. If you make sure the gear doesn't move I wouldn't even bother rechecking with a light if you don't have one.

FSM is the factory service manual. Any service manual basically, including the free ones in the FAQ.

batmanfc

Thanks a lot man. Yea the noise does sound like marbles in a can. I wasn't sure what it was and I no one had responded about it. I checked the timing today but I didn't take the CAS out like you said. I will do that for sure to check it. I did have it in time though with the first mark lining up with the needle evertime L1 fired. It didn't want to idle and missed horribly like that. I moved the timing a bit and its off but it will idle like that but it is still missing but not nearly as bad. How would I find TDC? Would the CAS be bad?
I thought that was what the FSM was but wasnt sure haha. Thanks a lot for the help.

batmanfc

Any other ideas?

batmanfc

Here is a video of how it runs in all 5 gears. It will not pull a hill and in 4th and 5th it bucks horribly if you try to keep a steady rate of speed and rpm. It only misses when it is under boos. and still doesn't idle right. Also, in 5th it will not accelerate much if any in 5th.
http://www.youtube.com/watch?v=9OmkgQ0Jybs

calpatriot

Closed loop is quite useful if you want to use the O2 sensor signal to determine if the loss in power is due to a rich or lean condition... also if it won't go into closed loop that can point to things that might be causing problems in open loop...

I have stethescoped my primaries, in spite of the fact that they are under the intake..

This is a process of eliminating possibilities. The idea that something is unlikely does not keep it from happening...

If AFMs never went bad, nobody would be offering rebuilt units.

Others have experienced power loss at high throttle/rpm due to fuel pump and filter issues, also fuel return line issues, and exhaust restrictions.

Many of these things may be unlikely. But they are easy to check and eliminate.

batmanfc

Still not sure what it is exactly. I'm starting to expect the AFM because it isn't the timing. Any other ideas?

calpatriot

If you hook up a lamp to the center pins of the check connector, and remote it to the cabin, you can watch the rich-lean status on the road during the event. This may tell you where to look next.

If the mixture goes lean at the onset of the bucking/loss of power, then you can look further into air and fuel delivery issues.

If it is rich throughout, it is more likely to be ignition.

When I diagnose similar things in my car I use two long two conductor cables, and bring back into the dash both the 'green lamp' and also the O2 sensor voltage.

If the green lamp goes out or O2 voltage goes below 0.5v anytime during acceleration, I would then check fuel pressure (especially under load), and TPS check & adjust.

If your AFM is the problem, the system should (famous last words) show a trouble code. Does it report any codes?

batmanfc

Thanks I will give that a try. No it doesn't show any codes. I'm losing my mind trying to figure it out lol.

batmanfc

If the wastegate was stuck would that cause this to happen?

calpatriot

In theory, a stuck wastegate would affect the amount of boost available, but it should not affect the air-fuel mixture. The ECU, having a boost sensor input, should be adjusting the mixture based on the boost which is present, whether or not the boost level is normal.

On the other hand, there are always unanticipated interactions in complex systems, especially since we do not have a map of the logic in the ECU.

That said, given your symptoms, I would be more suspicious of the boost sensor or the air flow sensor rather than the wastgate itself. The missing suggests either improper mixture or improper ignition. I think the most likely scenario is the car is going too lean once the boost comes in. This could be verified or discounted with the green lamp test.

If it is going lean, either the ECU is getting bad data as to how much air is coming in, or it is failing to deliver enough fuel for that mass of air.

Potential culprits: boost sensor, air flow sensor, ECU, clogged secondary injectors (not flowing to normal volume); inoperative secondary injector(s); bad/intermittent wiring to the secondary injectors. There also is a boost limiting feature in the ECU that cuts off fuel to the rear rotor if the boost exceeds a certain limit (I think I heard 6.5 psi, but not sure). If your boost is going past that number (wastegate stuck closed?), or the boost sensor is over-reporting the boost level, you could be getting into the boost limit mode (unless you have a FCD--fuel cut defender) installed.

But until you determine the condition (mixture, ignition) that is causing the misfire, you are essentially guessing.

calpatriot

OK--here's a link
http://www.teamfc3s.org/info/articles/fcd/diy_fcd.htm
that explains the fuel cut issue at the boost limit. This author says the cut to the rear rotor comes in at 8.6 psi which about 3.75 volts out of the boost sensor, if his graphs are correct.

Some possibilities here are 1) your boost sensor is sending an erroneously high signal to the ECU, an thereby triggering the fuel cut; 2) the ECU is screwed up, and is cutting the fuel to the rear rotor when it should not be.

If either is the case, it ought to show up in the green lamp test (lamp should go out indicating a lean mixture when the cut comes in), or you should be able to detect it either with a noid light on the rear injector or by using a stethescope on the rear injector.

HAILERS

Do you have a aftermarket boost gauge. If so, what is the boost figure that the engine cuts out at? 6psi, 7psi, 8psi, 9psi,10psi etc.

What is your exhaust like? Stock? Full open three inch?

Is there a fuel cut defender on the car? Called FCD in some places.

Do you know why you would need a FCD for a car with a full open exhaust? Say ..yes.

I'm not sure the video did much for me. I can't tell if you just let off the pedal at ???? 4000 rpms or if the engine died and then started running again after losing a grand of rpms or so.

Can you drive this car over 4000 rpm using light pedal and staying out of boost? Runs more or less good like that up to ?? 6 grand?

batmanfc

No I don't have one yet but on the stock gauge it can barely show any boost and all and it will start missing like there is no tomorrow.
Full 3 inch. It had it when I bought it and doesn't have the FCD yet but I am getting one this coming payday. Yea I know why I need one. If I had gotten it done I would have put the FCD on first. Just haven't gotten to it yet.

I didn't let off of the pedal at all. It runs doesn't miss if you stay out of boost at any rpm so if it doesn't get into boost it would go up to 6000 rpm. I haven't tried revving it that high while driving though. I didn't want to blow it up. But it still has a miss at idle or idle wrong anyway. It fluctuates a little almost sounds like it has a streetport when idleing.