Loveboat now driveable and good power but...

[matthew]

I've got the loveboat more or less straightened out. I reset the timing, this time with the spout connector out, to 10 degrees. Greatly improved power. Good acceleration. However, at low RPM with a load (uphill) in OD or high gear, there is a sputter even at steady rpm. I can't really hear it, but I can feel it. Like the engine is missing a little built, it's not a steady sputter. When the tranny kicks down and the motor spins up, it goes away. The condition worsens the longer the motor has run. (less bad cool, worse hot)

I was thinking it was possibly pinging, so I retarded the timing to 9 degrees and put in a tank of 93 Octane gas.

It is still there, and there is some roughness and missing to the idle once the engine is warm.

My compression is about 165 in all the holes, which when divided by atmospheric pressure of 14.7 equals a compression ration of about 11.2:1.
Pretty high.

I'm thinking maybe with all the HO mods, the old 14 lb injectors can't keep up? Just a thought.

To refresh anyone's memory, I did the HO conversion with the exception of the cam, injectors, and computer.

The car is very driveable. I took it to PA and back (4 hours). I'm thinking maybe I should buy a Kirban adjustable fuel pressure regulator and bump up the pressure a little to feed the higher compression holes.

[Grand Marquis GT]

The compression doesnt sound quite right....how far did you shave the heads and WHAT pistons are you running?

If you have 11.2:1 ratio tho, it prob isnt too streetable...

[grandpaslincoln]

I'd say so, lol

[matthew]

Stock E7's shaved 0.020". My compression gauge is an el cheapo Autozone deal, but it was consistent across all cyls. I'll throw it on the stock colony park motor for reference as a comparison.

[matthew]

Stock E7's shaved 0.020". My compression gauge is an el cheapo Autozone deal, but it was consistent across all cyls. I'll throw it on the stock colony park motor for reference as a comparison. Stock pistons. I too thought it was really high. I was expecting about 10:1 at most with the shaved heads.

[matthew]

Stock E7's shaved 0.020". My compression gauge is an el cheapo Autozone deal, but it was consistent across all cyls. I'll throw it on the stock colony park motor for reference as a comparison. Stock pistons. I too thought it was really high. I was expecting about 10:1 at most with the shaved heads.

[nitroracer]

If you suspect it to be the injectors take a look at your plugs to see if they are reading lean. I swapped out my 14lbers for some 19lb injectors because I thought the car was running lean after a head an intake swap as well. It had the same low rpm stumble. But I also think the improved air flow raised the powerband so you might need more rpm to get up those hills without the engine chugging.

[phayzer5]

unless you purposfully rebuilt the engine with high-comp pistons, there's no way you have that much compression...

[88grandmarq]

I seriously doubt its a fuel issue.
I would suggest an adjustable fuel pressure regulator with the stock injectors before you try changing the injectors.

The very first thing I would do is ensure the tune up parts are new or like new condition. this includes cap, rotor, wires, plugs, t/stat, air filter, PCV valve, screen and grommet and dont forget about the fuel filter.

Also, what spark plugs are you using. you are aware the E7 heads take a different plug than the E6 head, right?

check the ECM For stored trouble codes and check for any obvious vacuum leaks.

[gadget73]

When my motor was doing that it was bad plug wires. Agree with all the above advice, but still not really sure you need a set of 19 lb injectors. I'd try that as a very last resort. When the intake was off, did you replace the O rings on the injectors? it could be a slight air leak around one of them.

[matthew]

Yeah, I tried the holley adjustable fuel pressure regulator from summit, no change. The plugs were reading a little lean but no blistering or chipping, or aluminum speckles. The plugs, wires, rotor, cap, distributor, air filter, pcv screen, plug and valve, and distributor all brand new. I used the E7 spark plugs and gapped them to spec. I'm going to get a fuel pressure gauge. Maybe the fuel filter is partially plugged and needs replaced, but the odd thing is that I would expect that to cause trouble at high rpm. I'm only having the trouble at rough idle, and pinging under low rpm load. I'm going to gear up the rear, but I don't just want to hide the problem I intend to solve it. Could bad O2 sensors be the culprit?

[gadget73]

Possible, but the only real way to tell is with a code scanner. Are all the plugs evenly lean, or are some much more noticable than others? If its consistant, I'd probably say the whole fuel sys is running lean, if its not even than you have a vac leak someplace. If nothing cures it, go with the 19# and maybe tweak the pressure downward if that makes it run too rich.

Also, I hate to say this now, but disconnecting the vac line from the stock FPR would have bumped you about 10 psi, probably enough to tell you if an AFPR would be the solution. It wouldn't be a permanant solution as you'd lose your boost of pressure on acceleration tho.

[Pablito]

I also suggest that you check your TPS. Put an analog volt meter across it while you steadily advance the throttle. The needle should sweep across the dial smoothly. If you see any "spikes" or "dips" then I'd replace it.

Those "spikes" and "dips" are especialy noticable at low RPM's as a slight shudder or misfire.

-Paul

[88grandmarq]

Once again... you need to check the ECM for trouble codes and properly diagnose the problem, before you randomly guess and replace sensors and/or parts.

[TommyN]

Re: Loveboat now driveable and good power but...

My compression is about 165 in all the holes, which when divided by atmospheric pressure of 14.7 equals a compression ration of about 11.2:1.
Pretty high.

Stock 9:1 HO motors make about 150 psi cranking. 165 is not 11.2:1. Compression ratio and cranking compression are somewhat related, but I have never seen a formula that equates cranking psi to an actual compression ratio. Cam timing affects cranking psi. I have seen a rule of thumb that cranking compressions over 200 psi won't work with pump gas.