engine miss

[Shimy87]

Can't feel the miss in park, also hosed everything down again and no leaks found...its got to be Maf or O2. Also when driving and its happening the fp gauge was rock steady so not losing pressure.

[Steve Wood]

I would think if it was a mechanical problem, the miss would get worse under a load.

The chip should have a fuel curve built into it for part throttle operation.  The maf should provide air flow measurement to the ecm to control the fuel flow from what was programmed into the chip.  The O2 provides feed back from it's after the fact measurement and the ecm should fine tune the fueling to get it where it wanted it to be.  That is what I understand.  Therefore our two variables are really just the maf and o2.  Of course the fueling is also altered by the temperature sensor that goes to the ecm.  If the ecm temp reading is close to what the temp gauge reads from the water temp sender, then all should be good.

[Shimy87]

Got the new O2 sensor in, still kinda feel it. Does the air temp sensor effect fueling? It warm today at about 85 but that temp sensor reads 125 to 145. Its installed right at the air filter. Water temp on the gauge matches the SM reading

[Steve Wood]

The factory chip only paid attention to it at cold temperatures.   I believe Eric's chip use it more to affect fueling.  Hotter readings would tend to pull fuel out for a leaner mix.  I think I would replace it as it is cheap. Or it used to be anyway...

[Steve Wood]

swap them and see

[Shimy87]

I just ordered one, $14, and while I'm at it going to relocate the charcoal canister and pipe the air filter down in that area. Cut the plastic "floor" out there to give it the coolest air possible

[Steve Wood]

125 to 145 is not particularly hot for under hood air if the engine has been running long enough to warm up the air under the hood......

but if the air was a lot cooler than that,then it might be enough to lean it out....

The key seems to be that the O2s look lower on the car than they do on your own car....  cheap sensors are not killers to try...

Usually air leaks and such show up on the blms but really don't make the car act up in my experience, unless they are before the throttle body.  this one is really strange.

[Shimy87]

I never did check to see if intercooler had a leak???

[Steve Wood]

It's common on an old one...be a good idea to check

[gnonyx]

It's common on an old one...be a good idea to check

Very interesting, would also cause the increase of BLM as a vacuum leak?

[Steve Wood]

It can. It's unmetered air that was not measured by the maf.  Therefore the ecm does not give enough fuel. Then the o2 screams at the ecm to add more fuel in and the blms go up

[gnonyx]

I don't think I have any leaks with the intercooler since many years ago I did removed it to be clean, but I ever did check for any air leak. Since now I'm waiting next week for the delivery of the heater hoses, and the water hose the feeds the Throttle body. Both hoses are original, and although their look good on the outside I don't know how their look inside; Better safe than sorry.
So now I will remove the intercooler, and check for any air leaks and clean it again. Hopefully by the end of next week I will assemble all, check air leaks in the engine, and finally start and hope to see the BLM running normal or around 128.

[Shimy87]

Found 3 leaks in intercooler. Ordered a slic for mine and will swap my stock one into kids car. 

[Steve Wood]

When opportunity knocks, ... 

[Shimy87]

Got it switched in, finished the "cold air" induction and test drove....suces s!! No miss, runs very smooth and intake air temp runs about 10 degrees above actual air temp so happy with that. 

Prior owner put new springs in front but still had old in rear so it sat dragging its ass. We put some new ones in back and its got a nice stance back, about 1/2 inch taller in rear now than front.