ClubRoadster.net banner

1 - 20 of 35 Posts

·
Premium Member
Joined
·
306 Posts
Discussion Starter #1
So my engine starts to bog down around 3k putters for a bit then just takes off. People have been saying it's my fuel pump but I'm not sure, any suggestions? I'm getting spark and fuel at idle but I don't know how to diagnose while it running. Does anyone have any tips?
 

·
Premium Member
Joined
·
306 Posts
Discussion Starter #7
So it's a 91' 1.6l just turned 127k last week. So far I have changed the fuel filter with no luck problem kept on happening, so I started having a rough idle it would jump up to 1200rpm then almost die and just go back to the regular 800 rpm idle like nothing then repeat. So I cleaned the iac by running some carb cleaner through it letting it sit, ran the motor the ran some wd40 to lube things back up a bit. It seemed to help alot at first, the idle smoothed out and the problem seem to happen less. But now it back to it's same old ways. I have the ica screw all the way down and when I let go of the throttle it stays at 1200 rpm then bogs then goes back to 800rpm. If I let out the screw it does it even worse. And yes it bogging out again at around 2-3000rpm.
 

·
Registered
Joined
·
33 Posts
It kinda sounds like a sticky ISC or wonky dashpot. I would take the ISC out and give it a good cleaning. If you haven't replaced the plug wires, consider doing so as that fixes a lot of weird issues. If the trouble persists, see if you can borrow a known good (complete) tb from someone to test.
 

·
Registered
Joined
·
109 Posts
So you have power loss, do you pick power back up at higher RPM (say 4000+)?

Some other things to check would be any visible woblle on your crank pulley, also if you have a timing light check you timing, see if it's off.

If it's an early '91 it could be SNC failure... I just went through it (start halfway through this post):

http://clubroadster.net/vb_forum/showpost.php?p=1056643&postcount=51
 

·
Registered
Joined
·
262 Posts
So it's a 91' 1.6l just turned 127k last week. So far I have changed the fuel filter with no luck problem kept on happening, so I started having a rough idle it would jump up to 1200rpm then almost die and just go back to the regular 800 rpm idle like nothing then repeat. So I cleaned the iac by running some carb cleaner through it letting it sit, ran the motor the ran some wd40 to lube things back up a bit.
For starters I'd use something else to lube the IAC - WD40 might be good for dispersing moisture and OK-ish to free off parts, but it's not a good lubricant that lasts as it's got a lot of solvents in it that evaporate and the lubricant wears off easily. I'd use regular lubricating oil or gun oil for something I'd like to stay lubricated for a while.
 

·
Registered
Joined
·
2,488 Posts
So it's a 91' 1.6l just turned 127k last week. So far I have changed the fuel filter with no luck problem kept on happening, so I started having a rough idle it would jump up to 1200rpm then almost die and just go back to the regular 800 rpm idle like nothing then repeat. So I cleaned the iac by running some carb cleaner through it letting it sit, ran the motor the ran some wd40 to lube things back up a bit. It seemed to help alot at first, the idle smoothed out and the problem seem to happen less. But now it back to it's same old ways. I have the ica screw all the way down and when I let go of the throttle it stays at 1200 rpm then bogs then goes back to 800rpm. If I let out the screw it does it even worse. And yes it bogging out again at around 2-3000rpm.
shitty power up top implies timing is off, especially if you are having idling issues. with that said, you could also have a vacuum leak AND another seperate problem for the bogging.

Not sure if its the fuel pump, I am doubtful of that. They tend to cause problems at all RPMs rather than at one particular RPM.

Did you do a timing belt change recently? Also, get a vacuum gauge and check your vacuum.
 

·
Premium Member
Joined
·
306 Posts
Discussion Starter #13
I just checked the timing the other day and its perfectly at 10degrees. I have all the parts to change it but u have not done it yet cause I'm so busy all the time.
I just pulled code this morning an it's flashing a 17 according to this Code
Meaning
1
Ignition pulse
2
Ne signal
3
G signal
4
SGT signal (1.8L)
8
Airflow meter
9
Water thermistor
10
Intake air thermistor in airflow meter
12
Throttle position sensor
14
Atmospheric pressure sensor
15
Oxygen sensor (output too low)
16
EGR function sensor (1.8L)
17
Oxygen sensor (output not changing)
25
PRC solenoid valve (1.8L)
26
Solenoid valve (Evaporative canister purge)
27
EGR solenoid valve (vacuum)(1.8L)
28
EGR solenoid valve (vent)(1.8L)
34
34 Idle air control (1.8L)
36
Idle speed control valve

17 means the oxygen sensor isnt changing? Does that mean it's out? Should I replace it?
 

·
Premium Member
Joined
·
306 Posts
Discussion Starter #14
Oh and could the oxygen sensor be the reason for the stumbling?

And yes after it passes the 3000 rpm the power kicks in like normal all the way to redline, and if I'm driving it hard, above 3k it doesn't stumble at all.
 

·
Registered
Joined
·
2,488 Posts
Oh and could the oxygen sensor be the reason for the stumbling?

And yes after it passes the 3000 rpm the power kicks in like normal all the way to redline, and if I'm driving it hard, above 3k it doesn't stumble at all.
Well if the front o2 is not giving reading changes, then it certainly can cause the ecu to run like ****. at certain throttle positon (and in your case RPM since you have a non variable TPS), the ECU will go into open loop. Seems that perhaps its going into open loop and using a map rather than trying to keep a certain AFR.

Replace front O2 and see what happens. they are realllly cheap if you buy a generic and splice it in.
 

·
Premium Member
Joined
·
306 Posts
Discussion Starter #16
Alright, so I installed a new o2 sensor just now and drove it home. The difference is night and day, it even feels like I might have picked up some power. Acceleration is smooth and consistent. But, I'm still having idle issues. I hit the iac again with cleaner and lubricant but no dice. I'm thinking I might need a new iac. Anyone have one for sale?
 

·
Registered
Joined
·
2,488 Posts
Alright, so I installed a new o2 sensor just now and drove it home. The difference is night and day, it even feels like I might have picked up some power. Acceleration is smooth and consistent. But, I'm still having idle issues. I hit the iac again with cleaner and lubricant but no dice. I'm thinking I might need a new iac. Anyone have one for sale?
I don't think you need to do that quite yet. get a vacuum gauge and see how the vacuum is at idle. What is your idle behavior now that you have replaced the o2?

Also, buying IAC seperately is VERY expensive, if I were you I would search ebay for a miata throttlebody, most sellers forget to remove the IAC (or don't realize its a seperate unit) end up selling the whole shebang for <$70.

Otherwise, you are looking at well over $125 for an IAC.

Doubtful the fuel filter has anything to do with it, but if hasn't been replaced...
 

·
Premium Member
Joined
·
306 Posts
Discussion Starter #19
Replacing my fuel filter was the first thing I did. Had a new one sitting in my trunk for a while.
The idle with the new o2 is the same, it sticks at around 1200 rpm when I come to a stop. Then drops almost till it dies. Then goes back to 800rpm and stays there.
As for the problem with it bogging that's gone. Well at least for now. It's running much better.

Now I just need to fix that idle. I'm going to try and take it off and clean it.
Any advice? Sensitive thing to look out for?
 
1 - 20 of 35 Posts
Top