High fuel trim and pinging

[Gubachoo]

OK so I've spent some decent time so far and can't figure it out. I put a new CME 4.7 stroker in my truck in September. After break in it ran great and so I went on a long planned road trip while towing a small travel trailer. Things went great after a few hiccups (hose from TB to map sensor popped out, harmonic balancer that I stupidly didn't replace when doing the motor seperated, clutch master failed) but after 3000 or 4000 miles I started to notice a pinging.

 

I have an REM and saw my knock going up. Checked the sensor and the terminal was cracked so I replaced that (torqued properly and everything) but no change. It steadily got worse. I noticed my LTFT and STFT were both high. My LTFT is what I assume is the max of 166 because it's stuck there and STFT is between 100-170 driving and as high as 220 at idle. Most of the time so I'm very lean, causing the ping. My idle is also high most of the time, but not always suspiciously. Now here's where I thought I had it. Checked my manifold bolts and found one loose on the under side. Tightened it but no change. Just finished spraying all areas it could leak with TB cleaner to see the change in idle and I get nothing. Will try it again later with water as I know this will cause more of a noticeable stumble than TB cleaner. 

 

While doing the spray test I pulled off every vacuum hose and plugged the port with my finger to see if the idle dropped to normal indicating the problem was on that circuit but no luck. Also watched the REM at this time to see if the STFT took a dive. No luck on all counts. 

 

So it seems very likely that this is an installation error problem since I just had the motor out but keep in mind it wasn't immediate. I have larger injectors (forget which ones but I can look it up if important) but the problem wasn't here initially and grew worse over time so unlikely that's the issue. My o2 readings still switch but hang on the lean side more as you would expect. Everything else seems good and much is new with the engine swap. My last thought it that the bolt that loosened up allowed the gasket to blow out under if after hundreds of miles of not being torqued but as it's only vacuum I find that unlikely. It's also really hard to get in some of the spots where the manifold meets the block with a spray bottle. 

 

So that's where I am. I know how bad pinging and running lean is for a motor so I'm babying it and trying to get this solved ASAP. I have many (not all) of cruisers tips done if that makes a difference. Any constructive input is appreciated. Also, I'm on the road a bit so apologies in advance for possible sporadic responses.

[Gubachoo]

Picture: fuel trim at idle with knock and inj duty cycle. 

[Gubachoo]

Picture: knock sensor at 55mph while towing small trailer under light throttle. 5 mins after resetting knock memory with max and min (sorry, it won't let me post it right side up no matter how I try) 

[Gojira94]

I think the next step in the fuel delivery department is to verify fuel pressure.

[Gubachoo]

17 hours ago, Gojira94 said:

I think the next step in the fuel delivery department is to verify fuel pressure.

I'll do that but it doesn't quite make sense with the high idle unless it is a seperate issue (not impossible for sure) 

[ghetdjc320]

Check for vacuum leaks and fuel pressure 

[Gojira94]

16 hours ago, ghetdjc320 said:

Check for vacuum leaks and fuel pressure

 

A thought - do you think a ballast resistor with too much resistance might be excessively regulating/ restricting power to his pump? A bypass would be a quick and easy test in the field. Check KOEO pressure with it place, bypass, check again if a DVOM wasn't available? My 2 suspicions are a restriction in the lines (clogged filter or debris on the feed side) or inadequate fuel flow from the pump (weak pump, + feed or ground problem, resistor).

[Ωhm]

Since your fuel trims (both LT&ST) have added INJ PW time, what value (mS) is your REM showing for INJ PW? 

[Gubachoo]

Like I said, I'm doing this while on a road trip so apologies for the delayed response. This problem has taken a little bit of a back seat to my running light fuse blowing constantly while I try to find out why and then my headlight switch melting (see photo) but that will be done in the next few days

 

To answer some questions. Checked my fuel pressure and it is good around 30psi as per fsm. Under load and while driving. Up to 40 when the vacuum line pulled from regulator. Replaced my fuel filter just because it needed it and no change. Also jumped the ballast resistor, no change. 

 

I replaced the pump maybe five years ago when I did the tank. Put in a Bosch unit. I know that doesn't preclude anything but it seems good. I will check for vacuum leaks again more carefully in the next few days when the headlight switch issue is resolved but I'm getting close to pulling the manifold with the thought that the gasket is bad after finding that loose nut. 

 

Any other thoughts are appreciated 

[gogmorgo]

Headlight switch melting is going to be your fuse blowing issue. Make sure the pigtail hasn’t also melted. You’re lucky it only melted, mine set itself on fire.

 

As to the original complaint, does your engine builder spec an octane rating for your fuel, and have you tried running mid grade or premium? A stroker build will generally increase your compression ratio, which often will dictate a higher octane rating.

 

If it’s the first long trip you may be encountering some heat soak issues you wouldn’t see just doing shorter runs.

Have you pulled spark plugs to see what they look like? It’ll give you some indication of how the engine’s running.

 

Gasket is cheap and just as easy to replace as it is to look at. High probability you’ll damage it pulling the manifolds off. An exhaust leak will leave an obvious black stain and be an indication of an intake leak cause it’s the same gasket. Dribble some water over the manifold/head interface with it running, if the idle goes normal for a few seconds that’s the water plugging up a leak as it’s getting pulled through. Safer than spraying something flammable onto a running engine. 

[Gubachoo]

On 11/23/2023 at 7:56 PM, gogmorgo said:

Headlight switch melting is going to be your fuse blowing issue. Make sure the pigtail hasn’t also melted. You’re lucky it only melted, mine set itself on fire.

 

As to the original complaint, does your engine builder spec an octane rating for your fuel, and have you tried running mid grade or premium? A stroker build will generally increase your compression ratio, which often will dictate a higher octane rating.

 

If it’s the first long trip you may be encountering some heat soak issues you wouldn’t see just doing shorter runs.

Have you pulled spark plugs to see what they look like? It’ll give you some indication of how the engine’s running.

 

Gasket is cheap and just as easy to replace as it is to look at. High probability you’ll damage it pulling the manifolds off. An exhaust leak will leave an obvious black stain and be an indication of an intake leak cause it’s the same gasket. Dribble some water over the manifold/head interface with it running, if the idle goes normal for a few seconds that’s the water plugging up a leak as it’s getting pulled through. Safer than spraying something flammable onto a running engine. 

 

Thanks for the input. Yeah the headlight switch has melted the pigtail. Will have to repair with spades until I get to a junkyard to get a new one. Glad to have finally found the issue though. 

 

The engine I ordered specifically called for 87 octane but I ran a rank of 91 just to be sure with no change. Also keep in mind this issue came on after a few thousand miles so it is not in the initial build. I've pulled the plugs and they show a slightly lean/hot mixture but that's what I expected with how it is running. 

 

My plan for the afternoon is to use a water spray bottle to check for leaks again. 

[Gubachoo]

On 11/16/2023 at 4:45 PM, Ωhm said:

Since your fuel trims (both LT&ST) have added INJ PW time, what value (mS) is your REM showing for INJ PW? 

My injectors are between 14ms and 18 ms when at highways speeds at normal throttle in fifth gear. I never noted what they were before so do not know if this is normal. My stft sometimes goes as high as 200+ so it is trying to compensate for too much air (since I think the lack of fuel probability has been eliminated) and I need to figure out why. I can't do the gasket at the moment on the road so it might have to wait which is not ideal. I'm also afraid that my front pipe might not go back on as the studs holding it to the manifold were questionable when I put the motor back in (was on a very tight time budget so couldn't do it at that moment) so I want to do it when I can take the time to go over it well. Not in a Napa parking lot in somewhere Tennessee or Kentucky. 

[Ωhm]

I was wondering if INJ PW was way out of wack, but the times (mS) seem good. If you’re running in CLOSED LOOP (CL) then O2S sees a 14.7_1 Air/Fuel ratio, even with all the Fuel Trim adjustments. I always thought LTFT could climb to 256 before kicking you out of CL. You say plugs look LEAN, so now I wonder if engine timing has anything to do with PING.

[Gubachoo]

On 11/25/2023 at 5:45 PM, Ωhm said:

I was wondering if INJ PW was way out of wack, but the times (mS) seem good. If you’re running in CLOSED LOOP (CL) then O2S sees a 14.7_1 Air/Fuel ratio, even with all the Fuel Trim adjustments. I always thought LTFT could climb to 256 before kicking you out of CL. You say plugs look LEAN, so now I wonder if engine timing has anything to do with PING.

I have cleared it and had it go back to 128 ltft and then once it hits closed loop it climbs quickly to 166 and stops so it seems that's the max. I only have the narrow band stock o2 but it is switching which tells me it is at or near stoichiometry. The timing is not adjustable outside of cruisers clocking tip correct? I had done that years ago and double checked it when the engine went back in. My current plan is pull the manifold as soon as I can and do the gasket again. If it isn't that I'm out of ideas.

[Ωhm]

On 11/28/2023 at 7:14 PM, Gubachoo said:

The timing is not adjustable outside of cruisers clocking tip correct?

 

Yea. You can ADVANCE it one way or RETARD it the other way. Also, affects INJ timing and when to look for KNOCK.