Engine Occasional misfires normal for a HCI?

[AnthonyA1234]

Sorry guys another dumb question. I’m gapping the plugs right now and I’m wondering what’s the right way to do it. You can see when I fully slide the plug over the tool it’s actually reading the gap farthest left from the puck since the ground isn’t parallel. Is that where I want the gap to be .054 or should the gap be .054 centered over the puck?

 

[AeroCoupe]

You are splitting hairs here. Just be consistent with all of the plugs.

 

[AnthonyA1234]

You are splitting hairs here. Just be consistent with all of the plugs.

I mean it’s a substantial difference between the two, one is .054 and the other is at like .07. I’m guessing the spark would jump to the closer of the two anyway right?

 

[AeroCoupe]

Spark will jump the closest gap I.e. path of least resistance.

 

[Pinellas50]

Backfiring into the intake is called a lean pop. It's usually caused by the motor running too lean.

This could be a simple tune issue. I would check for vacuum leaks and/or possible dirty MAF wire. I am assuming the MAF is matched to the injector size you are using.

 

[AnthonyA1234]

So I got the new plugs in today. Car drives better now and a lot of the characteristics It had that I always thought were because of the big cam went away. To be more precise it no longer bucks at lower Rpms and feels less sluggish getting on the gas at low Rpms. I was so happy it fixed it until I pull out of the street my home is on and I gave it some gas and I heard one pop from the engine. Then as usual it ran great after that no pops.

I’ll be doing a smoke test tomorrow to check for vacuum leaks.

Below are pictures of the plugs I pulled along with my compression test numbers. If anyone could let me know if they see anything worth noting please let me know. There was some oil on plugs 1 and 3. The plugs only have around 500 miles on them.

 

[AeroCoupe]

Did you swap the HCI onto an existing short block? If so can you do a leak down test on each cylinder? Compression looks good but a leak down wells you a little more. With oil on the plugs it almost sounds like blow by and once the plugs foul the car runs rough. If the heads were new hopefully you can rule out worn valve seats and seals. Would be a piston ring issue possibly a PCV system issue?

Once the mechanicals are proven out then you can chase ignition issues like the distributor and/or it’s components and tha coil or the ECU.

 

[General karthief]

Clear the codes then drive it around doing some in town and highway time then check for codes.

 

[AnthonyA1234]

Did you swap the HCI onto an existing short block? If so can you do a leak down test on each cylinder? Compression looks good but a leak down wells you a little more. With oil on the plugs it almost sounds like blow by and once the plugs foul the car runs rough. If the heads were new hopefully you can rule out worn valve seats and seals. Would be a piston ring issue possibly a PCV system issue?

Once the mechanicals are proven out then you can chase ignition issues like the distributor and/or its components and tha coil or the ECU.

I believe it’s stock short block at least that’s what the guy I bought it from told me. hm I really hope it isn’t the rings. I noticed some oil coming out through the valve cover bolt holes. Is it possible that dripped into the spark plug hole? I’ll put some pics below.

Clear the codes then drive it around doing some in town and highway time then check for codes.

The car has never had any codes besides 94/44 which I believe I don’t have to be concerned about since I don’t have cats

 

[General karthief]

Oil from a small leak like that will not get past the spark plugs into the combustion chamber.
i don't see any real problems with those plugs, maybe a little darker on a couple, compression is acceptable, does it smoke (blue) at any point?

 

[AeroCoupe]

2nd the General's comments on the valve cover oil drips (not even gonna call those leaks). I still say do a leak down test on each cylinder as that confirms the mechanical side of the motor. With the short block being an unknown to you this would be one of the first things I would do but I do understand as not everyone has a leak down tester and air compressor handy. Another quick thing you can do is double check the PCV system and make sure it's in working order as it could either be contributing to existing issues or creating them.

Did you do another smoke test? If you do not mind I want to revisit the fuel system. You have a new Kirban FPR (solid FPR by the way), new fuel pump, new FoMoCo 24 lb/hr injectors, and a Pro-M calibrated for the injectors. Assuming you have replaced the fuel filter? What brand and flow rate is the fuel pump?

I am going to go back to fuel pressure settings, stock fuel pressure is 38-39 psi with the vacuum line unhooked/plugged and with the vacuum line connected it should be around 30 psi. You stated that yours is 38 psi with the vacuum unhooked/plugged and connected to the FPR. This is a problem as the fuel pressure should fall with the vacuum connected and then rise as you get on the throttle. I am not saying this is all of your problems but if it is idling at 38 psi and is should be 30 psi then the ECU is having to compensate for the additional pressure i.e. fuel at idle. Again, i do not know if this is enough to cause all the issues you are having but it cannot help.

 

[AeroCoupe]

If you are curious on Codes 44 & 99 this a pretty good thread on it. It would take removing or electrically disconnecting the solenoids behind the passenger side strut tower to get these codes.

Code 94/44 AGAIN!

I have a 90 LX, 5.0, that has had a 94/44 error code for a couple of months. I think I've done all the diagnostics correctly, but I just can't solve this one. I've replaced the smog pump because it had a bad bearing. I've tested both solenoids during a KOER test and both have voltage...

stangnet.com

 

[AnthonyA1234]

Oil from a small leak like that will not get past the spark plugs into the combustion chamber.
i don't see any real problems with those plugs, maybe a little darker on a couple, compression is acceptable, does it smoke (blue) at any point?

Nope, no weird smokes coming out of the exhaust.

2nd the General's comments on the valve cover oil drips (not even gonna call those leaks). I still say do a leak down test on each cylinder as that confirms the mechanical side of the motor. With the short block being an unknown to you this would be one of the first things I would do but I do understand as not everyone has a leak down tester and air compressor handy. Another quick thing you can do is double check the PCV system and make sure it's in working order as it could either be contributing to existing issues or creating them.

Did you do another smoke test? If you do not mind I want to revisit the fuel system. You have a new Kirban FPR (solid FPR by the way), new fuel pump, new FoMoCo 24 lb/hr injectors, and a Pro-M calibrated for the injectors. Assuming you have replaced the fuel filter? What brand and flow rate is the fuel pump?

I am going to go back to fuel pressure settings, stock fuel pressure is 38-39 psi with the vacuum line unhooked/plugged and with the vacuum line connected it should be around 30 psi. You stated that yours is 38 psi with the vacuum unhooked/plugged and connected to the FPR. This is a problem as the fuel pressure should fall with the vacuum connected and then rise as you get on the throttle. I am not saying this is all of your problems but if it is idling at 38 psi and is should be 30 psi then the ECU is having to compensate for the additional pressure i.e. fuel at idle. Again, i do not know if this is enough to cause all the issues you are having but it cannot help.

What’s the process for checking the Pcv system? It does have a new motorcraft Pcv valve.

Haven’t done the smoke test yet I’ll do it later today when I get home and let you guys know how it goes.

Yea filter was replaced with a motorcraft filter. Fuel pump was also replaced, 190lph walbro pump. I also changed the tank, cleaned out the fuel lines, and changed the injectors and regulator as you already know.

Oh no my fuel pressure does drop to 30psi with the vac line in and is 38 with it off and plugged. Sorry if I wrote anything to cause that misunderstanding.

 

[AnthonyA1234]

Something else that could be contributing to it. I changed the radiator to a lmr sve aluminum radiator and put a heavy duty fan clutch because my car was overheating In these hot florida months. However now when it’s a little cooler I’ve been noticing the temp gauge constantly reads here and never goes up to the middle like it would before no matter how much I drive it. Could this be contributing to why I’m noticing more misfires lately or is that reading within acceptable range?

 

[General karthief]

The stock gauge is a 'best guess', I got a inexpensive electric gauge and stuck it at the bottom of the dash cause I ain't cutting anything up to mount a gauge, some put the gauge pod on the pillar but that's kinda 'race car' for me. I can glance down and see the actual temp.
The reading on your stock gauge may be a little low but again, 'best guess'.
I think the midpoint hash on the stock gauge is about 200* but again, 'best guess'.
Disclaimer: this is my opinion and not based on any real mechanical experience.

 

[AeroCoupe]

Change the temperature sending unit. Mine did that and I put a new one in and the gauge went back close to where I was used to it being. Also, these cars came stock with a 192 deg F thermostat so running a colder one will move the needle.

Sounds like your fuel system is good to go. PCV system is pretty basic in that as long as the check valve is working and has a good seal the lower intake you should be good to go.

I noticed you have Motorsport valve covers. What did you do to replace the oil fill neck on the passenger side valve cover? Reason I ask is on mine I had a push in cap that was vented and I just capped off the old vacuum line that went to the stock filler neck. This allowed unmetered air to enter the motor and looked like this:

Fixed it by doing this:

Welded a TFS fill neck onto the valve cover and then drilled the neck and welded an 1/4" NPT bung on it so I could screw in a 1/4" barbed fitting to put the vacuum hose on.

Again, not saying this is your problem but all these small things add up.

 

[AeroCoupe]

Go to this thread to see how a Cobra intake should be plumbed vacuum and PCV wise as it may help.

Engine - Pcv delete questions

So I recently purchased a 1992 gt. I just got the car running and have been tuning it up. I went to replace the Pcv valve and crank case filter but then noticed that the T that the Pcv valve line goes into was covered off and the hole the line was supposed to go into on the right side of the...

stangnet.com

 

[Noobz347]

Code 44 is still a code you need to be concerned with particularly, since we don't have any after-cat 02 sensors anyway.

If you're throwing a lean code then either the sensor is bad or you're actually running lean. The cat doesn't come into it until [after] the sensor.


I'd be looking around for vac leaks and I'd be looking at those sensors.

 

[AnthonyA1234]

Change the temperature sending unit. Mine did that and I put a new one in and the gauge went back close to where I was used to it being. Also, these cars came stock with a 192 deg F thermostat so running a colder one will move the needle.

Sounds like your fuel system is good to go. PCV system is pretty basic in that as long as the check valve is working and has a good seal the lower intake you should be good to go.

I noticed you have Motorsport valve covers. What did you do to replace the oil fill neck on the passenger side valve cover? Reason I ask is on mine I had a push in cap that was vented and I just capped off the old vacuum line that went to the stock filler neck. This allowed unmetered air to enter the motor and looked like this:

Fixed it by doing this:

Welded a TFS fill neck onto the valve cover and then drilled the neck and welded an 1/4" NPT bung on it so I could screw in a 1/4" barbed fitting to put the vacuum hose on.

Again, not saying this is your problem but all these small things add up.

No my valve covers came with a normal screw on oil cap so I’m good there.

Did the smoke test just now and had smoke coming from three places. First I noticed was smoke coming out of the egr. Now this is something I saw last time I did the smoke test months ago and saw many different opinions. Some saying it’s normal and some saying it’s not. I went through 4 different egr valves and all of them did it so I’m just gonna say that’s normal.

Then after around 10 minutes of smoking it and looking for other leaks smoke started coming out of the dipstick which I believe is normal as well, I’d imagine it’s gonna start coming out of there eventually.

The final place I noticed smoke which is the one that actually had me concerned was there was a constant stream of smoke coming from behind the engine by the firewall. It wasn’t the Pcv valve but something around there. I’m guessing it’s the lower intake seal but if there’s anything else in that area it could be let me know.

I had a shop change that seal for me already about a month ago so it’s brand new. However I know that seal is a little tricky and they used those blue silicone seals which I know people advise against in favor of RTV.

I’m thinking I’ll just do the seal myself and probably change the water pump and seal as well while I have all that stuff out as insurance.

 

[AeroCoupe]

Have never used a gasket on the front or rear of the lower intake. Good bead of RTV and let it skin up for about 30 min then install the intake.

If the EGR leaks smoke then the engine can suck air into it the same route which is unmetered are going into the intake.