Voicing concerns

I’ve been trying to voice my concerns these last few weeks with my truck. Ever since the dealer has did my timing cover reseal, I’ve been having a few issues. One, they didn’t put some things back on correctly. There were missing bolts and the dipstick thing was loose. Most of that weird tick noise is gone now. I had 2 different mechanics resolve most of that. They checked my timing and put new tensioners, guides, and apparently the chains were still fine. I was willing to pay someone else to do it right and would rather not go to the dealership for anything else. They cause unnecessary issues and create new problems that weren’t there before. The dealer faulty work caused it to have a vacuum leak (running a bit lean based on fuel trims). Air cleaner hose and breather hoses were loose. Also I needed to have intake manifold gaskets (which they supposedly replaced but seemed like they didn’t). I’m always left with a feeling of uncertainty. I’m keeping a close eye on my fuel trims. It has came down some but still looks a bit high to me.

 

This is disappointing, I hope it gets resolved for you.
My truck has so many electrical issues the dealers just refuse to work on it, and I'm okay with that after seeing horror stories like this.

 

Yea, my exhaust definitely smells a bit rich during cold start but without the black smoke. After it warms up enough the smell goes away.

 

I feel like I was better off not even taking my truck there for the timing cover reseal. It’s not like I was loosing any noticeable amount of oil. Had to be a very small leak if that. I got suckered into believing I need to get it done right away all while paying for poor quality work.

 

This is how people lose faith in dealers. I haven't heard much good about any of em except for from the 3rd Gen guys, and even a lot of them are getting the F around.

 

What he said, and be firm, yet polite. But, also, be firm. Lol. And, if they don't resolve it, there are other steps you can take afterwards, but first things first.

 

Is this with ethanol-free fuel or regular e10 that needs a little extra fuel to burn stoich?

 

Regular fuel with ethanol

 

The ltft's are always positive on my '16 every time I have checked them. Once with the ethanol calc at zero with ethanol free fuel I was still seeing around +5. Being a flex the ethanol calc can make it a little screwy so it isn't always repeatable either. I've seen +28 ltft with a 60% eth calc on full swill e85 and it still didn't throw a cel.

Fuel trims are calculated by rpm as well so it varies as you drive

 

10 is right at the end of the acceptable range. Need way more data to know if you have an issue. FYI, the term for long term is seconds/minuites, not days, so you need to collect a lot more data to determine if you have an issue or what that issue may be. You can see the LTFT bounce around as you drive.

 

What other data should I look at? Earlier, I did the rev test, looking at rpm’s and seeing what the fuel trims are doing. The LTFT, which is slightly higher than +10%, goes down some when I rev it and returns to a little above +10 when it’s just idling. I did have a vacuum leak and the guy that fixed it was telling me it should take a couple of drive cycles for it to relearn and optimize the fuel trims. Seemed like he resetted everything, my gas mileage needs to go back to up. Before he even did that the LTFT was above +25% and the cel was on for that. I’m slowly noticing improvements since then.

 

Fuel trim data is real time and resetting doesn’t change anything after a minute of driving. Fuel trims are NOT learned, it is purely an output for diagnostics. It is a rolling computation of how much more or less fuell is being delivered, relative to the main system fuel table. Your mechanic doesn’t understand how the ecu works. Where are the ltft’s? I would drive around while observing the ft’s. -10 to 10 is considered an acceptable range though I prefer to get within 5. If you are 10 at idle, it could be many things. However, when the lean condition is worse at idle, I always start with vacuum leaks. Possibly you had two and your guy only found one and gave up.

 

New dealer.

 

This is where my fuel trims were at after a driving around for a bit. I appreciate your knowledge, it seems that the people that worked on my truck aren’t competent enough to pinpoint a problem nor understand how things work. Disregard that high negative value -85.9 that is has on the range for LTFT bank2 (there’s no way it was that value)

 

8 and 10 for ltft is considered acceptable. These change constantly, so best to observr them while driving. You should not drive THEN observe. You want to be looking at STFT in all sortsd of different driving conditions and see what it does. You want to know when it diverges from 0 and by how much. If it is always bouncing around between -5 and 10, then you have no major issues. As long as it stays below 10, must mechanics wont bother diagnosing further.

 

Ok, so I drove and had the live data run while driving. While driving my LTFT are normal but at idle it’s a bit higher than normal. At idle I saw 11.7% for bank 1 and 13.3% for bank 2. Would that be problematic? Otherwise the truck is driving fine.

 

I wouldn't call it problematic, but it does suggest a small vacuum leak or leakage in intake pipping downstream of the MAF. Vacuum is strongest at idle, so ruuning lean only at idle is indicative of a leak.

 

Do you know any other areas where a vacuum leak could occur? I already had the intake manifold gaskets replaced, the 3 ventilation hoses that come to a T, MAF sensor, oxygen sensors were done not too long ago. Only other things left is pcv, brake booster, fuel injectors. I don’t really see it being the brake booster. I was also wondering if an exhaust manifold can cause this. There’s no poor idle or anything like that but something is definitely affecting the fuel economy. It only seems to improve a little if I do long distance driving based on the average mpg on the computer. Another thing I notice is that my LTFT becomes more positive over a longer period after driving. So, in the morning it’s normal as it’s idling and remains normal during the drive. Then as I continue driving through the day (it’s normal while driving) and check it at idle (it becomes a slightly more positive like +12% or so and comes down when I press the gas) I will have someone else check it out and have another smoke test done.

 

exh leaks can cause the O2 readings to go lean, if upstream of the sensor,, thus adding fuel and killing MPG. Holwever, you would see higher FTs across the board. It is much better to watch the STFTs, as they react immediately and will give you a better sense of the problem. Best way to find a vac leak is with carb cleaner. Spray it on any area that could be a leak source. If you get a slight RPM rise, the area you sprayed has a leak. Don't spray on exh, just intake stuff.

My tacoma had leaks at the flages of exh manifold. No real FT issue, but lots of ticking whenever I stepped on the gas.

 

Once again, I appreciate your help and I hope I’m not disturbing you too much about this ordeal. I watch both the STFT and LTFT, don’t see any issues with STFT. LTFT seems to become more positive as the engine gets warmer and goes down when it’s under load(while driving, accelerating, revving). Everything seems to point towards a vacuum leak although I don’t hear any hissing noises. Whatever seems to be going on, it could be
why my truck hesitates a little bit when accelerating from a stop. Once it gets going it’s fine. I will finally take my truck to a reputable shop and let them check it out. I decided to give it a little time to see if it’ll improve. The few dealers that are a reasonable driving distance aren’t no good (the good one is a least 2 1/2 hours away). I’m now more selective over who I choose and read the reviews (especially the bad ones). I found a good independent shop with a great rating and I’ll give them a try and see what they can find. Some others don’t want to diagnose if there isn’t a cel.

 

Sorry, I was too quick with my response last time. Total FT= LTFT + STFT at any given moment.. So, your total trim at idle is 19. That indicates a lean condition. If this lean condition gets better (i.e. lower total FT) off idle, it is probably a vac leak. If the same or worse off idle, it is probably a different cause. there are many things that can cause a lean condition. sorry, but this is not something easilly diagnosed over the internet.

best way to find a vac leak is spraying carb cleaner anywhere near a potential leak source. given that the trims have enough control to get a good AFR, this leak is not likely your source of poor running, but that is a generalization.

 

Great advise from the above poster Ir172 concerning a vac leak problem that you seam to have. I would look to an independent shop too help you make the fix. Find one that can perform a smoke
test on the engine. Takes about an hour , but that testing can find vac leaks just bout anywhere they may be hiding.

 

Update: vacuum leak appears to be fixed now. I decided to wait some time to see if it’s actually corrected and doesn’t reoccur. So far my fuel trims are looking more normal at idle and aren’t showing anymore indications of vac leak. Apparently my intake manifold gaskets were still leaking even after having them replaced by the second mechanic. The shop I took it to believes that too much sealant was applied to mating surface, it should only be applied to where joint meets the gasket. Due to what happened the first time, the gaskets came out of place some. I’m guessing it shouldn’t have been done like it was in the picture here. Clean the mating surface, make sure it’s dry all while having the intake ports covered during the process. I don’t know much myself but I do agree with the shop that the entire mating surface shouldn’t have sealant like that. Are we correct? Sealant shouldn’t be used around the entire surface. They used the Fel-Pro, not sure if they’re the best or equivalent to the oem.