stumbling DOHC

[mykel78]

Hey people, I may have a question for ya...
I have a 94 MX3 DOHC (I presume it to be RS). I recently did an even swap with an engine supposedly from Japan. I've heard these run higher compression which then produces more HP, this is still a myth to me, any ideas?
hmmm, list of new parts:
Intake Gasket
Valve Cover Gasket
Plugs and Wires
Distributor and Cap
O2 Sensor
Used set of Injectors (fewer miles than the old)
New Clutch
SOHC Intake from E-Bay (yes it works on DOHC)
slight problem here: nothing for the vac line that used to go to the airbox to hook up to. Therefore it is dangling at the moment, problem? It dangled for a year or so before the swap without a problem...

[mykel78]

So, seriously, nobody has a clue on this???? Fouling plug? runs a little rich, it seems. Why? What all could cause this to run rich? But not evenly in all cylinders? mech or elect problem?
C'mon there seem to be many sharp MX3 fanatics here giving some decent advice. And nobody has even a clue???

[Custommx3]

are you using the correct ECU?

[mykel78]

Well, terrific, thank you for acknowledging my questions!! I'm using the original ECU, I've never removed it. Would I need a different ECU for this engine? Everything under the hood hooked up perfectly...

[Rope04]

To me...It sounds like a firing prob....Is the gap between all four plugs correct and check your cap and rotor, there may be a few nicks in it to keep it from firing correctly...But that's all I can think of...I haven't had my 4cyl in a long time and if it were the k8 I certainly would most likely be able to tell you whats wrong,but try it if not run some codecs on it at your local auto shop

[mykel78]

Yeah, the plugs are good, I actually just got back from a drive with another new set, gapped correctly. I'm doing a test as it seems the injectors may be a little off, testing according to the amount of carbon on the plugs. and the rotor is the only part I have not yet replaced. Note that now the problem seems present at idle and under load.

[Rope04]

HMmmmm....if it's the injectors clean them or dump some injector cleaner in your tank, Check your fuel filter and fuel lines...Yes do your rotor....Timing may slightly be off, get it checked, and your Vaf If you have the 1.6 dohc I believe they switched to the Vaf from the 92 1.6 Maf

[Rope04]

I meant to say also check your Vaf

[mykel78]

It's a cone type MAF. Checked out testing procedure in a Chilton, horrible instructions. Tried to test but the listed procedure seems useless. Thanks though!! Know of a procedure that works??
I hate this book, of all auto manuals chiltons sucks. I wish Haynes would make one for the MX.

[schwankesmx3]

clean out the MAF with carb cleaner

[Ehpl]

If everything checks out ok. Check your engine tempeture sender (not temp sender for guage) , if it is bad your engine will try to compensate for thinking its the wrong temp. A bad oxygen (o2) sensor in the exaust manigold will cause a engine to run rich. these should be replaced around 125k mi an can ruined by contaminants before this point "never spray silicon or teflon spray around your intake it will ruin your hot wire mas and your o2 sensor"

Eugene L
1.6DOHC
N.S.canada
http://www.cardomain.com/memberpage/552384

[mykel78]

thanks!! I'll clean the MAF and replace the temp sender. It's only 26 bucks. Would this cause the engine to run rich?? if the temp sensor is sending erroneous message telling the ECU to run it rich. not telling the ECU it's hot...makes sense, thank you.

[mykel78]

update: Cleaned the MAF, no effects. Have to go to the Mazda dealership for the temp sender, neither AZ or O'R has the right part (which BTW, they don't carry the proper valve cover gasket either). Thanks to those who tried to help!! Problem is still present...

[manowar821]

uh.. That vaccume tube thats hanging? CONNECT IT.
I asked about it recently, and everyone tells me it is NEEDED, and that the engine can run funny or not start at all.
I don't know if this is true, but it sounds like it.
As one person said "mazda doesn't just put random tubes in that have no use... LOL"

[monty73741]

i had this problem, bought a new MAF from japan, not that, then it turned out to be the disty


jason