Won't pull over 4k

[mboyek]

This is a 89 smec, stock. Timing set at 8^.

It will rev over 4k, especially if I loose traction in 1st or rev in neutral BUT if I have traction and nail it it acts like a rev-limiter at 4000 rpm. Pulls hard till then. I can't think of any limp mode that cuts off at 4k. Cam's are strait up and 2.0 cams. No relevant codes. From a roll I nailed it on some cinders and it bounced from 4k to 4500 and back, just like a rev limiter.

Right now I'm thinking of getting the A/F gauge hooked up(installed just needs wired up) and maybe run around with the knock sensor unplugged. I'm running 3-5 psi of boost now with 93 and its cold. When I was running around with a OTC4k scanner it seemed to be picking up allot of false knock, would that make it fall on its face? But I wouldn't think it would be constant at 4k. And it was part throttle knock

Should I open or close the gap of the plugs? I'm running NGK's at 0.035".

Should I try a new coil?

I guess I should check the fuel pressure too.

Everything is close to stock settings, the 2.5 T1 ecm should be able to keep up at less than 5 psi.

Frustrating. It seems like its computer related because its so consistent, I would think a dying fuel pump or false knock would not be a perfect rev limiter at 4k. And it runs beautifully till then.

[bradp]

Unhook the knock sensor and see what it does.

[mboyek]

No go, pulled the knock sensor out. Still getting "soft" above 3800 under load. I did get some odd "back fires" with the knock sensor unplugged, definitely not spark knock and this is the only thing changed. Never had that before.

Its 18^F here, the Holset spools at 2k and the 'ol van does pull pretty decent at 5 psi till this problem.

I think I'm going to try a different set of spark plugs, what are you guys running??


I have a set of champion rn9cy's, but they do not fit down the spark plug well because there too fat. I'm running NGK BKR7ES-11.

What would be a close to stock champion that would fit down the spark plug well? NGK's are not easy to get around here, I had to order those in.

[mboyek]

OK just ordered some NGK R5671A-9. But I'm running low boost for the break in, not sure if they will be too cold.

Any other ideas?

I know I should not be beating on the van until I get a few hundred miles on the fresh rebuild but the noises that holset make are too much fun.

[mboyek]

From the NGK website:A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase.

So at 5 intercooled psi I would assume I'm 150 hp on a good day, which is very close to stock, so I should run stock 2.4 plugs. (pulling ##'s from space, but whatever)

Also:for domestic manufacturers (Champion, Autolite, Splitfire), the higher the number, the hotter the plug. For Japanese manufacturers (NGK, Denso), the higher the number, the colder the plug.

This clashes with allot of info I've been reading on TD and here, so I think when people have been switching to ngk's, some have been going hotter than they want. more knowledge direct from NGK: The heat range numbers used by spark plug manufacturers are not universal, by that we mean, a 10 heat range in Champion is not the same as a 10 heat range in NGK nor the same in Autolite.

I'll give those racing NGK plugs a try when they come in, maybe a new coil at the same time.

[mboyek]

Its a fuel issue.....

[shelbyplaya]

check the MAP and TPS.

what coes are you getting?

[moparzrule]

No A/F gauge? Whats it show when it starts dying?

[mboyek]

No A/F gauge? Whats it show when it starts dying?

WOT rich till 4k then lean.

Hooked a fuel pressure gauge up, 4000 rpm or so the pressure starts dropping below 50psi.

Going to try a return-line style rail. Having a 5' line on the fuel rail connected to the gauge gave me a "reservoir" which gave me a few hundred extra rpm till lean.

[moparzrule]

Well it's either the FPR or fuel pump to be loosing pressure, it's about the only options.

[mboyek]

Well it's either the FPR or fuel pump to be loosing pressure, it's about the only options.

I'm running a 84 TI FPR, the reason I am thinking its the rail setup over the pump is I was able to keep the pressure up for a few hundred extra rpm with the fuel pressure gauge attached to the rail. So the long hose w/pressurized fuel acted like a pressure reservoir as it is beyond the FPR and T fitting.

http://i441.photobucket.com/albums/qq135/daytonaer/GEDC0065.jpg
http://i441.photobucket.com/albums/qq135/daytonaer/GEDC0068.jpg

Going to see if I can mod the 2.2 rail w/reg to fit.

[shelbyplaya]

check your cam timing.

[moparzrule]

I'm running a 84 TI FPR, the reason I am thinking its the rail setup over the pump is I was able to keep the pressure up for a few hundred extra rpm with the fuel pressure gauge attached to the rail. So the long hose w/pressurized fuel acted like a pressure reservoir as it is beyond the FPR and T fitting.

Going to see if I can mod the 2.2 rail w/reg to fit.


Not necessarily. With a larger reservoir like you describe, the fuel pump has that all pressurized and it takes longer for the pump to start not keeping up anymore. Kinda hard to explain but I hope you know what I mean.

Have you changed the fuel filter recently?

[moparzrule]

check your cam timing.

Thats the first thing I thought, but he said both were straight up. Plus the fact that he's loosing fuel pressure is just real evidence that that is the problem.

[mboyek]

Thats the first thing I thought, but he said both were straight up. Plus the fact that he's loosing fuel pressure is just real evidence that that is the problem.

I changed the filter a few years ago, its moved maybe 50 miles since then. I have a new filter I was planning on putting in when I depressurized the rail to modify it.

The ability to dial in the cam timing is one of the reasons I went with the FWD gears, it is zeroed. I really don't want to change the fuel pump. That tank is rusted up there and full of '93. Hopefully changing the fuel feed setup will fix it.

If I put low pressure on the FPR (say 5 psi) at idle would I be able to see the rise in pressure? I do see the change when I hook up vacuum. Other than flooding the engine, would this be a good way to test the pump?

[shelbyplaya]

I changed the filter a few years ago, its moved maybe 50 miles since then. I have a new filter I was planning on putting in when I depressurized the rail to modify it.

The ability to dial in the cam timing is one of the reasons I went with the FWD gears, it is zeroed. I really don't want to change the fuel pump. That tank is rusted up there and full of '93. Hopefully changing the fuel feed setup will fix it.

If I put low pressure on the FPR (say 5 psi) at idle would I be able to see the rise in pressure? I do see the change when I hook up vacuum. Other than flooding the engine, would this be a good way to test the pump?

It my be directly related to way you have your fuel reg and feed lines hooked up. Are you 100% possitive that you have your in/out of the reg right?

have you checked your lines to the MAP and are you getting any codes?

[mboyek]

It my be directly related to way you have your fuel reg and feed lines hooked up. Are you 100% possitive that you have your in/out of the reg right?

have you checked your lines to the MAP and are you getting any codes?

Thanks for the suggestions.

I have zip ties on the map vacuum lines now, that fixed the idle somewhat, but was done a bit ago. the little line between the solenoid and map was loose, and I swapped the MAP out when fighting a bad ecm, so that's all good now.

codes are 12, 22, 55. Set timing, haven't driven allot, so that's fine.

Honestly I have NO idea if the FPR is hooked up correctly. I think I just did it that way because it fit that way. :confused:

That is something to look into, but I don't know how to tell which way is correct. Its a brand new FPR, I hooked the line from the rail on the side and the return line on the bottom, there is also a threaded portion which I used to mount it with a slim nut on the bottom.

I'll look through some of my literature to see if I can find anything on which way the FPR should be mounted. Do you have any experience with the log FPR routing?

[shelbyplaya]

Thanks for the suggestions.

I have zip ties on the map vacuum lines now, that fixed the idle somewhat, but was done a bit ago. the little line between the solenoid and map was loose, and I swapped the MAP out when fighting a bad ecm, so that's all good now.

codes are 12, 22, 55. Set timing, haven't driven allot, so that's fine.

Honestly I have NO idea if the FPR is hooked up correctly. I think I just did it that way because it fit that way. :confused:

That is something to look into, but I don't know how to tell which way is correct. Its a brand new FPR, I hooked the line from the rail on the side and the return line on the bottom, there is also a threaded portion which I used to mount it with a slim nut on the bottom.

I'll look through some of my literature to see if I can find anything on which way the FPR should be mounted. Do you have any experience with the log FPR routing?

I dont no. I have the tryed tested and true method. I qwould sugest going the same route. It looks cleaner and helps make things flow better.

[moparzrule]

http://i441.photobucket.com/albums/qq135/daytonaer/GEDC0065.jpg



I just noticed this. Why do you have this T'd here? You have the fuel tank return line on the correct nipple on the FPR, but your feed line is messed up. You shouldn't have the T anything here. Run the pressure line right to the rail, and the return from the rail goes into the FPR.
Can I get a pic of your rail setup?

[mboyek]

The fuel rail has no return. :nod:

http://i441.photobucket.com/albums/qq135/daytonaer/GEDC0062.jpg

I'm pretty sure the FPR is not hooked up backward. Too bad, that would have been an easy fix.

I think I have a spare rail I can modify for a return line. But the van blew a brake line today....

[moparzrule]

Well thats odd, how the hell do the stock 2.4's maintain fuel pressure then?


Even with the way you have it setup, I still don't think it would be loosing pressure if the pump was healthy or the FPR was faulty. But seriously when was the last time you changed to fuel filter? I've had them clogged before, so much that it was making me run lean. The filter sock inside the tank can also get clogged as well, I never had that problem though. I never tried to push my cars with the stock pump though, always went right to the walbro.

[mboyek]

Well thats odd, how the hell do the stock 2.4's maintain fuel pressure then?


Even with the way you have it setup, I still don't think it would be loosing pressure if the pump was healthy or the FPR was faulty. But seriously when was the last time you changed to fuel filter? I've had them clogged before, so much that it was making me run lean. The filter sock inside the tank can also get clogged as well, I never had that problem though. I never tried to push my cars with the stock pump though, always went right to the walbro.

Filter was changed 2 years ago, less than 50 miles. Yes its possible its clogged with crap, I drained the tank but still. I will be putting a new filter on before I mess with the rail.

I'm not trying to push this setup with the stock pump, I'm trying to run 3-5 psi of boost for break in.