Under 4k Engine holds back horribly when cold

[vsofouk]

OK... So the car is really sluggish when the engine is cold below 4k. It feels like it's falling on its face. I did a full 60k on it in the spring (it has 66k on the clock now).

No CEL or codes

I ported the intake and added BBB's during the time of the 60k too btw since I had everything off.

When I added the the high flow cat and the catback (with new 02 sensors) it got better

When I added the 73mm MAF (using the same sensor) it got worse

WIll the LPM tuning chip take care of it or do I have another underlying problem.



Before I did the 60K it had a similar problem - i noticed oil leaking in the plug wells - after the 60K the symptom did feel different. But I had the BBB and the ported intake on it already.

Once it's warm it doesn't hold back nearly as bad, however I feel that the low end still doen't pull as strong as it did when I 1st got the car. When it's cold outside it does run better. And 3rd gear is amazing now!

 

[shotime1994]

Did you use the c&l maf? They are garbage. Did you reroute the wires correct?

 

[whiteman_01]

Why is it above 4k when its cold? Whatever you car may be screaming at you, I agree.

 

[220ksho]

A dirty MAF will do bad things especially at cold IME. Use some MAF cleaner spray and let the computer dial in the optimum fuel map.

How's your MPG?

 

[rubydist]

Why is it above 4k when its cold? Whatever you car may be screaming at you, I agree.

This is a very good question, and over 4k should be avoided until the oil is warmed up.


I think one of the significant causes of low power at startup is that the rings are stuck. the aluminum pistons expand more than the cast iron block when at temp, so when cold the pistons/rings are too loose if the rings are sticky, resulting in more blow-by and lower power. of course, the faster the engine is running, the less of an issue that is.

my 92 acts this way, and here is why I think its a sticky ring issue - if I start it for 45 seconds, and then park it overnight, it will puff a big cloud of smoke in the morning. however, if I drive it till warm and park it overnight, no puff of smoke. bad valve stem seals should cause a puff every morning. my next plan is to get some AutoRx and try that cleanup program before I tear into the engine.

 

[jayro]

The Auto RX is a good idea. Also, what maf are you running? Did you just put your stock sensor into a 73mm housing? If so then your PCM doesnt know the correct amount of air that is coming into the engine. Your MAF/PCM is set up for the 55mm. Try cleaning your sensor and reinstalling the 55mm. Make sure you reset the PCM when you do this. With your mods I would recommend staying with the 55, but if you want to change mafs go with an 80mm from a Mark VIII and get an lpm. Even with the LPM/80mm I would recommend logging some a/f readings to make sure it is tuned correctly. If you dont have a way to log them most dyno shops will provide them for you with a set of dyno pulls.

And x2 on checking your gas milage. This can give you an idea if your a/f is out of wack. When my O2's went south my car was throwing a lean code, but the air was so thigk with fuel it burned your eyes. Plus my milage was Terrible.

 

[Mr Anonymous]

When I added the 73mm MAF (using the same sensor) it got worse

Throw that ************* MAF in the trash.

And clean your MAF filaments as mentioned; when you put the electronics back in your stock housing.

Why is it above 4k when its cold? Whatever you car may be screaming at you, I agree.

This is a very good question, and over 4k should be avoided until the oil is warmed up.

That's just plain stupid. Unless by "cold" he's saying "freezing", once the car has run for more than 30 seconds and the oil pressure is up it's just fine to BEAT THE SHIT OUT OF IT. I can't believe that in this day and age there are still people who believe all these ******** old wives' tales about being "gentle" on cars. Anyone who thinks this way should sell their SHO and by a Corolla or Aveo or some shit.

 

[msteiny]

I agree with the MAF Sensor housing being too big. My example of this comes from my 06 GT Mustang. I installed a cold air intake and the kit came with a different MAF sensor housing. The housing was oversized by 5 mm. You wouldnt think it would make a difference right, I turned the key and it ran like crap, Granted the computers today are a lot touchier but it knew something was wrong and it start throwing lean codes. After a couple phone calls I had to neck down the housing size to the stock diameter or reflash the computer. I sleeved the housing and now all is well. Like you even said in your first post "it ran worse after installing the 73mm ". I know most people think more air is a good thing when it comes to an engine, which is just an air pump itself but too much air can be a bad thing. Especially when its mixed with fuel and the computer is trying to compensate for this when it thinks its only got a 55 mm hole at the top to breathe from when actually its got a 73 mm hole.

 

[vsofouk]

Ok will try putting the stock MAF back on until I get an LPM - have an 80MM sitting around here somewhere.

Gas mileage when I do about 60% city is between 20-21, on a trip I took recently (80% hwy on the tank) I averaged 22-23 mpg - and i was over 80mph most of the time.

I've never had white smoke come out of the tail pipe btw, I periodically check for things like that.

 

[jayro]

Ok will try putting the stock MAF back on until I get an LPM - have an 80MM sitting around here somewhere.

Gas mileage when I do about 60% city is between 20-21, on a trip I took recently (80% hwy on the tank) I averaged 22-23 mpg - and i was over 80mph most of the time.

I've never had white smoke come out of the tail pipe btw, I periodically check for things like that.

Make sure you reset the PCM and clean it with MAF cleaner so you start with a clean slate. Your highway milage sounds a little low for an mtx. With my 3.0 I got almost 30mpg with the cruise control set on about 80mph. I wonder if your PCM is dumping in fuel to try and compensate for a ean condition?

 

[trainguy1989]

Make sure you reset the PCM and clean it with MAF cleaner so you start with a clean slate. Your highway milage sounds a little low for an mtx. With my 3.0 I got almost 30mpg with the cruise control set on about 80mph. I wonder if your PCM is dumping in fuel to try and compensate for a ean condition?

I don't know. My 91 3.2 MTX with a fresh front and top 60k only averages 19 -21 in city and 22-23 on the highway at about 80. And that's with the cruise control too. It has new o2 sensors, and port and polished intake with BBBs. No vacuum leaks. Pull the IAC plug the car dies. Never figured it out.

 

[jayro]

I don't know. My 91 3.2 MTX with a fresh front and top 60k only averages 19 -21 in city and 22-23 on the highway at about 80. And that's with the cruise control too. It has new o2 sensors, and port and polished intake with BBBs. No vacuum leaks. Pull the IAC plug the car dies. Never figured it out.

maybe there is a difference because its a 3.2. I havent checked my milage since my swap. All I know is that my old 3.0 got 29.xx on an all highway trip.