It's Running, Kinda...

[Maxx Mazda]

Well, finally turned the key today, and it ran on the brand new engine. Did all the "first start" things for a new engine, yada yada... Anyways, took it out for a test drive and it ran like a BEAUT for about 20 mins of really gentle driving. So, Oil press, AFR, all temps, lookin good. So I'm doing like 15MPH in the residential area, so I swerve around a bit to mix up the gas that's been sitting in my tank all winter. (Been 7 months) and all of a sudde, the carstarts to bog, and my AFR's go past 16.0:1 which is all mywideband shows me. So I'm likw "wtf, over" and decide to head back home (about 2 blocks away) to see what's up. So I'm about halfway there,and all of a sudden the hesitation stops, my Wideband goes to 13-15 (fluctuates in there) and the car drives normally. Drive for 2 more mins, andit starts doing it again, then without warning it returns to normal.

Like what the **** is going on? I'm thinking bad gas maybe, since it sat for 7 months without an engine, and it only happened after I "stirred" it up. Might also be my DSM AFC but at no time did I enter boost to activate it, so I canalmost rule that out. It's not the fuel pump as my fuel pressure was about 45psi the whole time. Tomorrow I'm gonna pump all the gasout of it and throw in 5 gallons of premium to see ifit fixes it. But yo i nthe mean time, has anyone got any suggestions?

 

[meinp5]

I don't really have any suggestions but are you sure all vaccum lines and electical lines are connected properly? I would go with your first instinct about bad gas. Congrats on getting it running again!

 

[azian6er]

sounds "fuelish." check all the injector harness clips as well as your connections to your ecu/maf.

I think it is a fuel issue, however bad gas i doubt is the cuplrit. I would bank on a loose injector clip or wires at or near the ecu.

My car had the same issue a while back and it just went away after a while.

-Bry

 

[s6m1l88]

7 months! wow! its very possible it has started to varnish! Get some new premium gas in there ASAP. An octane booster wouldn't hurt either.

What octane is said fuel? If its under 90, this is probably the case.

Quoting here:

Protect Against Fuel Varnishing

If you dont use at least a tank of gasoline a month, you could be risking damage to your engine...

A fuel varnishing problem could develop from either storage over the winter, or if you don't operate it on a regular basis. This fuel varnishing and the use of old fuel makes the engine run poorly.

Fuel varnishing / old fuel can affect engine performance. An engine with varnish build-up may start but run like it needs a tune-up. It surges - accelerating and decelerating

 

[Maxx Mazda]

Well, if it was an electrical connection, would my CEL not come on? Cause it didn't. I'm gonna pull the fuel line tomorrow, and hook up a jumper to the fuel pump wire in the diagnostic port as per the FSM and pump all the fuel out of the tank. Then I'm gonna throw 5 gallons of 93 octane in (that's what is in there currently) and see how it goes. I will double check my AFC map, injectors, injector plugs / harness and all vacuum lines. At idle, I'm only pulling 12" of vacuum, so I may have a vac leak somewhere.

 

[GhostMercury]

wow 12 is pretty bad. i hope you get it all figured out. good luck it though i cant wait to see some dyno numbers and stuff liek that

 

[Maxx Mazda]

Oh ya man, like this engine is BRAND new. Still only has like 28 mins on it lol! Got a few kinks to iron out still.

 

[GhostMercury]

yea im scared to rebuild for that reason

 

[s6m1l88]

You should pull around 18 inches of mercury at idle

 

[Maxx Mazda]

Yup. I used to before the build. Thinking I forgot to cap a nipple on my 626 mani somewhere... I'll use my boost leak tester and find the bastard, don't you guys worry...

 

[Maxx Mazda]

Update: So I did a boost leak test and found that my vacuum leak and my fuel problem may be part and parcel. I discovered that there was a fairly substantial leak around my #3 and #4 injector seals. (Where the injectors seal to the intake manifold.) So I'm gonna fix that up and retest. Will let you know how it goes.

 

[azian6er]

Update: So I did a boost leak test and found that my vacuum leak and my fuel problem may be part and parcel. I discovered that there was a fairly substantial leak around my #3 and #4 injector seals. (Where the injectors seal to the intake manifold.) So I'm gonna fix that up and retest. Will let you know how it goes.

had a feeling ;-)

 

[GhostMercury]

thats exact same thing happened to me when i did my 626 manifold. try and get an extra hand in there to help. o and if the manifold is on the braket take it off cause it pulls the manfold away from the block and causes a leak. (well it did for me)

 

[Maxx Mazda]

Ya I put my manifold on befotre the bracket. So I had to shave down those plastic "spacers" to get rid of the leak with my Perrin rail, but it worked. I now pull 17" hg at hot idle.

The lean condition still exists however, so I'm thinking one of two things. Either my AFC is coming on too early and it's map is ****** or something, or I really do have bad gas. So, I'm gonna drain the tank right now and fill it with 5 gallons of new gas and see what's up. I'll be back on after to update you guys.

 

[GhostMercury]

17 idle still seems low...but i could be wrong and its just my cars thats ****** up

 

[Maxx Mazda]

**** me I'm still at a loss. It's still going WAY lean and dying. I checked the wires on my O2 sensor, etc. I might have to get another sensor or something, I dunno.... Until then, gonna drain all the old gas out and try that. We'll see how it works out.

 

[sandspeed]

the same thing was happening to me because my primary 02 sensor was cooked. I replaced it with a brand new mazda oem sensor and the car runs great. How old is your primary 02 sensor?

 

[Maxx Mazda]

100,000 Km's on it (about 60,000 Mi) Since I had to extend my wires for it, I'll jsut use my leftover secondary O2 sensor (that is not connected at all btw) and use it.

 

[GhostMercury]

hopefully that works..

 

[Maxx Mazda]

HA HA!!!!!!!!! I GOT IT!!!!!!!!

Turns out that the fact that it was intermittent as well as reproduceable helped me quite a bit. Turns out, I had the vac. lines on the Purge Solenoid reversed, so when the ECU was expecting fuel vapor (and in turn cuts the injector cycle down) it wasn't getting any, hence the lean condition. Hooked the lines up properly, reset the ECU, and voila!

So far I have 28Km on my new engine, and it's already becoming smoother and smoother. Baby driving in a sweet car sucks, but in the end it'll be worthwhile I'm sure.

At startup (hot) the car stumbles for a few. secs and then comes out of it to normal idle, I was told that my agressive cams combined with the Walboro pump can do that, since for the first 10 secs or so at startup the ECU goes off a predetermined fuel / timing map anyway, and that it needs some time to adjust a bit. As long as I wait about 10 secs before pulling away, it's golden, so it just givesd me enough time to put my seatbelt on and find the right MP3 to play.

I dont' suspect this is the last snafu I'll run into with this new engine, so I'll keepo you guys posted lol!