Hesitation and fluctuating idle. Running out of ideas.

antimarlin · Post by **antimarlin** » June 14th, 2006, 2:58 pm

Idle problem started recently with idle occasionally dropping to a point just above stalling. Also hesitation while accelerating.

Cleaned throttle body which did not fix problem. Instead the idle now jumps all over the place still almost to the point of stalling.

It is not my coolant temp sensor, plugs, wires, or dist cap.

The TPS multimeter readouts are all within specs with the whole continuity thing. Right now I have raised the idle by turning the TPS. IT now idles like crap but is not droppng to the point of stalling.

I also think that I received a "throttle sensor" error when doing the "on board diagnostic". Does this mean that this needs replacement. (All tests seem good)

I really do not want to bring to a mechanic. Any suggestions at all.

mazdamx3sohc · Post by **mazdamx3sohc** » June 14th, 2006, 3:03 pm

did you recently do a motor swap?

ariesdude · Post by **ariesdude** » June 14th, 2006, 3:05 pm

antimarlin wrote:Idle problem started recently with idle occasionally dropping to a point just above stalling. Also hesitation while accelerating.

Cleaned throttle body which did not fix problem. Instead the idle now jumps all over the place still almost to the point of stalling.

It is not my coolant temp sensor, plugs, wires, or dist cap.

The TPS multimeter readouts are all within specs with the whole continuity thing. Right now I have raised the idle by turning the TPS. IT now idles like crap but is not droppng to the point of stalling.

I also think that I received a "throttle sensor" error when doing the "on board diagnostic". Does this mean that this needs replacement. (All tests seem good)

I really do not want to bring to a mechanic. Any suggestions at all.

Reset ECU and check codes properly - Check for Vaccum leaks. Does this bad idle happen all the time or only when engine is warm? When was the last time the O2 sensor was changed? When was the last time Coolant Temperatture sensor was "changed"?

antimarlin · Post by **antimarlin** » June 14th, 2006, 3:25 pm

No Recent motor swap. 275 K on motor.

Coolant temp is new and problem only happens when engine is warmed up.

I have never replaced O2 sensor ever. (can i test this with multimeter)

I gues I would need a code reader to properly check codes?

Spotted · Post by **Spotted** » June 14th, 2006, 3:51 pm

Which temp sensor did you change? 1 wire or 4 wire? 1 wire is for guage 4 wire for ecu. You need to replace the 4 wire sounds like if you haven't, but also check for vac leaks like posted above.

antimarlin · Post by **antimarlin** » June 14th, 2006, 4:18 pm

I replaced the actual coolant temp sensor. (2 pin connector with at least 3 wires, probably 4, can't remember)

I guess it could be vacuum. There are no leaks but I did notice something odd. The EGR valve with the sensor on it has the vacuum hose coming out of the bottom plugged with a bolt. I think the hose that was plugged into it just sits there. If I hook it like (I think) it should be the car stalls out.

Also this has been unhooked for over a year with no problems until recently.

Is there any way to bypass EGR or is that someone has already done?

Any more suggestions? And thanks so far .

ariesdude · Post by **ariesdude** » June 14th, 2006, 10:23 pm

no need for code readers
- here's the procedure for reading codes -
http://eunos30x.com/info/CEL%20Codes%20 ... mplete.pdf

http://eunos30x.com/info.html

I suggest resetting the ecu first and drive around for a while and then check for codes.

antimarlin · Post by **antimarlin** » June 15th, 2006, 10:23 am

I just read up on how to clear codes and have 1 question that someone can hopefully help with.
Step 2 of clearing codes says "ground test connector with jumper wire...."
Can someone explain this?
Or is step 1: "Disconnect negative battery cable and depress brake cable for 5 seconds" sufficient?

ariesdude · Post by **ariesdude** » June 15th, 2006, 12:54 pm

step 1 is sufficient

hobbypete · Post by **hobbypete** » June 16th, 2006, 1:41 pm

There are 3 temp sensors. Did you replace the one under the intake manifold. It feeds the ECU and is critical once the engine is hot. EGR input would make the intake hotter, so it sounds related. But read codes first.

ariesdude · Post by **ariesdude** » June 16th, 2006, 1:54 pm

DOHC engines (94 RS) have only 2 temp sensors - one for the gauge and one for the ecu - the ecu controls the fan.

hobbypete · Post by **hobbypete** » June 16th, 2006, 4:16 pm

You're right, of course. Sorry about the confusion.

What do the spark plugs look like? Maybe you have a fuel pressure regulation problem, not an ignition problem. Have you gone down this road?

antimarlin · Post by **antimarlin** » June 17th, 2006, 8:46 am

I am going to look into the fuel delivery system but am thinking it's not the fault. (Could be dead wrong of course) I just replaced the fuel filter which wasn't much fun(Got my hand stuck about 20 times)
Inspection is also due In 2 weeks: tie rods ends, rear struts, CV boot, brakelines. Got struts done but the brakelines will not be fun. CV boot will suck too even with the "quick boot" thing I bought.
Of course I have to fix this idle problem as well because it is driving me nuts. Hasn't let me down yet though.

Thanks again for the advice!

MX-3.com

Hesitation and fluctuating idle. Running out of ideas.

Hesitation and fluctuating idle. Running out of ideas.

Re: Hesitation and fluctuating idle. Running out of ideas.