PDA

View Full Version : no power up top



Murphy
08-06-2011, 04:07 PM
92 spirit 3.0 v6 543

The engine is really loosing power up top. If I floor it, the engine will get to about 4000-5000 RPM and just stop depending on the gear/load. in neutral or 1st gear I can hit the red line. I think my cams might be advanced. When looking at the timing mark on the pulley, is TDC in the center of the circle? Mine is a few degrees off from the circle...

I was having this problem before my recent timing belt change, but it would happen at about 5500 RPM in 3rd gear, and it wouldn't always do it.

Is there anyplace else I should look aside from cam timing? What else would cause the ecu to pull ignition timing?

raccoon
08-06-2011, 04:10 PM
knock maybe, bad injector. fuel pressure.

Sundance 6g72
08-06-2011, 04:11 PM
from ED's site


Contrary to what you may have read elsewhere or considered, you will not eek out high end performance or low end torque by setting the cam a full tooth off in either direction. 1 tooth equates to about 9 degrees. To fine tune the power band, you would want to adjust the timing +/- 5 degrees max. It is possible however based on the sprockets, and belt you are using for the marks to be a small fraction of a tooth off. Just make sure it is as close as possible.

RoadWarrior222
08-06-2011, 04:14 PM
If timing is good enough, list of suspects should include, MAP, TPS, fuel filter and/or pump.... though I also got some crap in the optical disk once that made it funky.

---------- Post added at 04:14 PM ---------- Previous post was at 04:13 PM ----------

Oh, clogged cat, loose muffler baffle, flattened exhaust can also be culprits.

Murphy
08-06-2011, 04:30 PM
oh ya I forgot to run the codes. Next time I take it for a drive, I'll watch the A/F.

---------- Post added at 04:30 PM ---------- Previous post was at 04:28 PM ----------

Are there any options to go catless? Will a turbo DP work or would it be possible to 'test pipe' it?

RoadWarrior222
08-06-2011, 04:59 PM
Well it should have a donut in a hemi joint before the cat, so if that doesn't seem too rusted up, you could unbolt it there for a test.... be friggin loud though.

turbovanmanČ
08-06-2011, 05:51 PM
I would vote on plugged cat or fuel system issue, IE bad pump or plugged fuel filter.

Hook a vacuum gauge up to the intake, manifold vacuum, note readings, go for a drive, if you WOT it and experience pressure in the intake, you have a plugged exhaust system.

Sundance 6g72
08-06-2011, 10:57 PM
oh ya I forgot to run the codes. Next time I take it for a drive, I'll watch the A/F.

---------- Post added at 04:30 PM ---------- Previous post was at 04:28 PM ----------

Are there any options to go catless? Will a turbo DP work or would it be possible to 'test pipe' it?

turbo downpipe? wouldnt do you any good on a 3.0

when i ordered my fwd catback exhaust, i also had a magnaflow straight through muffler. i pulled the cat off and put the muffler in its place and then ran the exhaust off the muffler and it fit alright but not perfect. Im not a perfectionist so i called it good.

---------- Post added at 10:57 PM ---------- Previous post was at 10:53 PM ----------

not sure if this is practical or even the right thing to do. Disconnect the exhaust at the manifold and go for a quick drive. This is if you cant check the exhaust the correct way shown above ^ ^

Ondonti
08-07-2011, 02:13 AM
disconnect and test, sure. Not gonna kill you.

Murphy
08-12-2011, 12:12 PM
Just checked the cam timing, looks bang on. I thought it was off before because I thought the timing marks on the crank were 2* each.

codes: 12,15,55 15 is the SDS because i dont have it connected to the ECU right now.

A/F - when it hits the wall the A/F sits at full rich and drops off and comes back about once a second

I haven't checked the cat yet

Murphy
08-12-2011, 12:57 PM
I put a boost gauge on the intake and took it for a drive. The car wanted to act normal today and I was able to redline 3rd without a problem.

RoadWarrior222
08-12-2011, 12:57 PM
Mouse nests in the intake :D

Murphy
08-12-2011, 01:23 PM
I was wondering if there was something weird with my intake, I have a CAI on it, maybe I'll take it off, make sure its clean and try a different filter

turbovanmanČ
08-12-2011, 01:51 PM
.

A/F - when it hits the wall the A/F sits at full rich and drops off and comes back about once a second

I haven't checked the cat yet

That's normal, they go pig rich at WOT.

Just for shitt's and giggles, check your fuel pressure.

Murphy
08-12-2011, 03:43 PM
took it out again, it was hitting a wall a 4-5k again. The boost gauge didn't go above 0.

guess i'll check the FP. I put the pump in less than 2 years ago and i was reading 55 psi

Murphy
08-12-2011, 04:05 PM
FP is 54psi with the vac line off. I don't think I can keep it hooked up while i'm driving...

turbovanmanČ
08-12-2011, 04:06 PM
took it out again, it was hitting a wall a 4-5k again. The boost gauge didn't go above 0.

guess i'll check the FP. I put the pump in less than 2 years ago and i was reading 55 psi

Its supposed to be at 43 psi. 55 is for a turbo 4 cylinder. No wonder its falling on its face, its just too rich.

Murphy
08-12-2011, 04:11 PM
I also have a MSD SCI box with a blaster 2 coil, what are the chances that that would be causing the problem?

turbovanmanČ
08-12-2011, 04:12 PM
I also have a MSD SCI box with a blaster 2 coil, what are the chances that that would be causing the problem?

It could be see post 17.

Murphy
08-12-2011, 04:30 PM
its been at 54 psi for about 2 years now and it hasn't started causing a problem until a couple weeks ago. How can I fix this? new FP regulator?

---------- Post added at 04:30 PM ---------- Previous post was at 04:25 PM ----------

According to the FSM stock is 48. Still high but 7 is a bit closer than 12.

RoadWarrior222
08-12-2011, 06:29 PM
I also have a MSD SCI box with a blaster 2 coil, what are the chances that that would be causing the problem?80% better than the stock ignition doing it...

Ondonti
08-13-2011, 05:01 AM
Still try the downpipe but the MSD = not reliable for many people.

Big_P
08-20-2011, 04:51 PM
if it's easier, pull out the O2 sensor and drive it, instead of lopping off rusted exhaust bolts.

Murphy
09-05-2011, 12:23 PM
The car has been good lately, but it was REALLY bad last night. At one point I could redline 3rd gear, and 2 minutes later I would hit the wall at 5K in first. I really hate inconsistent problems like this... I haven't tried tried disconnecting the cat yet or MSD yet.

Sundance 6g72
09-05-2011, 01:08 PM
when i ran my stock computer with 33# injectors i would get a 10:1 afr (min my gauge will read.. probably even richer than 10) and i could not hit the limiter at all. way to rich

you dont have a wideband? Maybe sometimes your 02 reads correctly and maybe sometimes it does not.. and when the car trys to guess your afr is assumes 48psi and not something in the 50s.. this is just a guess.

Murphy
09-05-2011, 01:34 PM
it is possible. The O2 is also decently new. Maybe i'll try the one out of my daytona. I don't have a wideband in this car.

Sundance 6g72
09-05-2011, 01:42 PM
i would just fix the fuel pressure for sure then. It should always be too rich when WOT though because the ecu dosnt tune that part.

Murphy
09-05-2011, 01:56 PM
so how can I get the FP down? Should I get a new regulator?

Sundance 6g72
09-05-2011, 02:11 PM
that would be my guess.

also, your vacuum line going from the fpr to the plenum is in tact right?

Ondonti
09-05-2011, 11:33 PM
I don't think any talk about being rich has anything to do with your problem. Don't be too lazy to try the easy stuff but somehow have enough energy to chase your own tail.

Murphy
05-01-2012, 08:09 AM
So an update on this problem...

Swapped the rail and regulator with one from the junkyard and the fuel pressure is STILL ~54psi. I also put on a 58mm TB, a plenum without the center divider, 3/4" spacers and spun the intake around.

When the ECU is first powered on (first connect the battery) the car runs GREAT! Once it starts 'learning' it wants to dump tons of fuel. About 2 days in its dumping so much fuel that I've killed the engine hitting the gas trying to take off from a light. I can watch the it idle with my dawes device sitting at blue and occasionally come down to green, which is like .96+ volts at the o2. It seems to be learning better and taking out fuel now, but this whole learning thing is really annoying. I've tried 2 different ECUs, a 93 and 94 5 speed ECU, I might try my stock auto ECU. The only codes have been 12,35,55. 35 is a fan thing...

I noticed my fan isn't coming on. This did happen a few months ago and I figured it was due to my SDS being unhooked. I hooked the SDS up again and it seemed to be working the past couple months. Now the fan isn't coming on again. I have a manual fan switch hooked up and it tosses the code for a bad relay as soon as I hit the switch.

So, I'm thinking since it isn't a consistent problem, its not a restriction anywhere like the cat being clogged. Since unhooking the battery seems to help, I think its the ECU's learning curve. What would cause the ECU to think I need more fuel or pull timing? When I get a chance I will try bypassing the MSD and see if it makes a difference.

Sundance 6g72
05-01-2012, 12:17 PM
i think coolant temp sensor will pull timing if its unhooked? isnt that how base timing is set? i never did it.


try running with tps and map sensor unplugged from the harness. same with o2. the car should default to limp mode and run off the table (do this after diconecting the battery)

that might get it drivable and have a spot to start.

c2xejk
05-01-2012, 12:17 PM
Have you put a scan tool on the car to see what the ECU is seeing for the O2 sensor?

The fact that it seems to learn the injector pulse width larger, implies that the ECU is seeing a lower voltage signal than the A/F gauge...

Murphy
05-01-2012, 04:14 PM
I've been thinking the CTS might be screwy, which would explain the fan no coming on. I think the temp has a large effect on timing and fuel.

I don't have a scan tool, but my cousin should have I can borrow. I really would like to see what my ECU is seeing and try to determine what its thinking.

Sundance 6g72
05-01-2012, 04:52 PM
if you didnt flip the plenum, cts change would be easy :P


i ran a chevy temp sensor with my stock ecu when my megasquirt got screwy. it idled really lean until it warmed up, then all was fine. Thats completely irreverent though...

if the fan isnt coming on, id suspect cts as you just stated. but i still think its worth it to force it to rely on open loop. not like it can hurt anything. It makes sense too because the car runs "fine" when you turn it on for the first time after resetting the ecu. so reset it and FORCE it to not learn and trim the map.

Ondonti
05-01-2012, 09:58 PM
My scanner sure helped me out.

Try unplugging your 02 also. Then there is no learning. It wouldn't be learning if the o2 wasn't telling it something that probably ain't right.

Murphy
06-10-2012, 07:47 AM
I THINK i got this somewhat figured out.

So it seems what was happening, was the coolant was boiling over from the fan not coming on, then the CTS wouldn't read the temp correctly. I would refill it when changing the battery or ECU or whatever, which is why that seemed to help... So now it is running fine, but the fan still isn't coming on. I've been living with the manual switch for now.

The odd thing is, when this problem started last year, I wasn't having a problem with the fan or loosing coolant.

RoadWarrior222
06-10-2012, 08:32 AM
Kinda sounds like it's had/got air trapped in there... either that or you've got a funky waterpump fail where it's sometimes moving coolant, sometimes not..... probably due to the impeller being loose on the shaft, or the belt slipping when it catches on the block or something.

Sundance 6g72
06-11-2012, 01:02 AM
yeah i think the ecu should pull timing if it thinks the cts isnt reading right

Ondonti
06-11-2012, 05:09 AM
Hope your headgaskets are okay.

Time to check the relay system (try manually jumping the relay) etc. See what part of the system is not doing its job.