Bogging/lack of power/hesistation

[Kalashnikov]

My car sat for a couple months while I replaced the nose on it. I noticed a few weeks/month ago that there a seeming lack of power/hesitation when you floor it off the line. Once it hits 3k it takes off like normal. When doing a brake stand it feels like complete ass and doesn't go above 3k. The other day I tried and it started to bog then it ripped up like it should. Did another, and it went up without any issues. The other day I tried and the bogging was back.

No CEL, new TR6 plugs, new fuel filter, just put in Granateli connectors. Mileage is about 110k. I also put a JLT in a couple weeks ago which didn't have any effect on the issue. Mileage has also dropped significantly. 18 is about the highest I can get mostly highway when before I could get 21 or 22.

Also have a Lidio 93oct tune, second cat delete, muffler delete.

[jwibbity]

im gone take a guess and say maybe one of the plugs you got was bad or COP

[Krytin]

Clean the maf but check for loose intake tube conections and vacuum hoses/conections..

[Kalashnikov]

I replaced all the COPs but the issue is still there. i Still have to clean the MAF. Intake is fine and I'll double check vacuum hoses.

[justbob]

Two common things to check are the IAC, and the EGR (and the associated DPFE)


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[martyo]

I'd look at your fuel pump if the car sat for a few months.

With today's gas fuel pumps go bad fast. Very fast.

[Billy]

I'd look at your fuel pump if the car sat for a few months.

With today's gas fuel pumps go bad fast. Very fast.

Interesting info. Never heard that before. I knew that gas with higher ethanol content can make pumps go bad but I didn't realize it was anywhere near that fast.
My car sat for several months with no fuel stabilizer and was fine. I guess I must have gotten lucky.

Is there any way to test the pump without actually taking it out of the car and bringing it somewhere?

[na svt]

I'd look at your fuel pump if the car sat for a few months.

With today's gas fuel pumps go bad fast. Very fast.

A bad fuel pump would not affect fuel mileage. MPG would also be unaffected by a bad IAC.

[Kalashnikov]

I seafoamed it the other day then added the rest of the can to the tank. Also got my new tires put on last week and an alignmenet monday and still only getting 18.25mpg. I didn't see any broken or loose vacuum lines either.

The fuel pump was replace by the PO and in my experiences, when they diedthey don't work at all.

It is strange that this seemed to start only after the car sat for a few months. I will pull the plugs and check them. With my luck one of them is funked up!

[Mike M]

I'll go MAF cleaning and check the fuel pressure with gauge. The only way it would be the EGR is if it was opening too soon or too much, you could pull the vacuum hose off it to eliminate that problem for testing but I doubt it highly.

[Kalashnikov]

I just did a few runs. I sprayed the EGR with carb cleaner. It didn't look very dirty. Problem still exists. The surging is most apparently mostly in the 1500-2k range and is particularly worse in the middle of that range.

On one of the rolling accels I did, it seemed like it was running excellent but then felt it like the bogging came back after.

I'll have to clean the MAF tomorrow. I'm wondering if O2s might possibly need replacement.

[Pat]

I believe the storage factor is the key and injectors may have fouled. Maybe use some high powered injector cleaner or have them cleaned separately.

I don't think it would be the O2 sensors, would throw a code.

A corroded MAF sensor is certainly a candidate. Since there are three things needed for combustion, Air, fuel, spark and you have changed both the spark and are working on the last of the air components, it leaves only the fuel component.

I'm thinking that since Fuel is a petroleum compound, it may break down, chemically, and solidify in parts of the fuel delivery system. A working theory (or not).

[Billy]

He ran seafoam through the gas tank.
If that didn't clean out the injectors then they're probably beyond repair.

If I were you I would see if I could borrow a really good OBD-II scanner. Most shops have cool portable scanners that can datalog all sorts of info and tell you all 4 narrowband o2 readings, fuel injector loads, maybe maf tables too.

[Marauderjack]

Sounds like a stuck EGR valve.......mine did the same surging!!:argue:

Replaced EGR valve and it's like a different car!!:beer: :D

[Kalashnikov]

Well I just did a little data logging. I kind of just played around and picked PIDs. I'm sure there are some inappropriate ones. From what I can tell, fuel pressure and MAF counts appear to be ok. What are some other PIDs I should log and is there a guide that will give me a little more detail about each of the PIDs?

BTW, the min fuel pressure was when I revved the car in park to 4500 (limited).

[dmjarosz]

Im not sure about your bogging issue but your decrease in fuel economy might be from winter blend fuel. It's getting to be that time of year when refineries are switching blends. I know I've already seen a drop in my fuel economy.

[Kalashnikov]

This has been on going since August so I don't think that is an issue. The fuel, 3/4 of a tank, had been in my tank since the begining of May til about early to md August when I started driving it again.