99 N/A 1.8 NB just rebuilt with idle issues

[pdsman53]

Hi Guys,
Just completed a Naturally Aspirated 99 NB 1.8 internal rebuild.
I removed the engine, stripped externals and gave it to a builder for him to do the internals (Rods/Pistons/Rings/Bearings/Oil Pump) and let him box up the Oil side. I then refitted all the external bits and reinstalled it.
It already had been running fine with extractors/O2 sensor relocated, EGR delete, A/C delete, BP5A intake Cam....prior to the teardown.

The initial start-up was successful...oil pressure/cooling all good.
I've run it for probably 60+ mins between 2000-3000rpms, as part of my run-in procedure.
...it idles OK on cold start-up....(for just a few seconds as a check...reluctant to let it idle for more than a few seconds, during Rings bedding in period).
...but it won't idle when warm (stalls)...so it's difficult to run any diagnostics.

I haven't replaced anything like throttle body/sensors etc...so was expecting that the OEM ECU would do everything that it was doing prior to the teardown.
I unplugged and reconnected the TPS/CAS, made sure the CPS was set to the right gap etc....the only thing I noticed was the engine vent pipe had hardened and cracked (maybe air entrainment?), fixed that...but no difference.

It's always possible during the teardown and storing of external parts that they could get damaged I suppose (like maybe O2 sensor), but nothing is obvious/apparent.

I got the builder to box up (to make him responsible for the internals, particularly the oil side...Timing was part of his box up), OEM...Cam gears and Timing plate.

I ran a diagnostic port check and received the following LED 'blinks'...(1-long/1-short), (1-lg/4-sh), (1-lg/7-sh), (1-lg/9-sh).
I assume that equates to codes 11, 14, 17, 19 ??
14 appears to be Atmospheric press sensor???
17 appears to be O2 sensor
...but what are 11 and 19??
any ideas??

I tested the O2 sensor, which appears to be working fine...
Ran engine until Hot....multimeter on the connector Signal side showed 0.9+ volts and dropped quickly after switching engine off.
Heater Cables showed that there is continuity.

I noticed that the "no touch Idle Screw" was not in contact with the throttle stop...so I jumped the Diagnostic Port, then screwed the "no touch Idle Screw" down to the stop, with a 0.002" feeler gauge under the Butterfly plate....then backed out the Air Idle Screw about 1/3 turn (base idle)....the engine Idled OK!!....but still seems harsh on idle.
Maybe the builder was out one tooth on timing??....if so, could that cause the warm idle issue?? I thought not, considering cold idle is OK....but could account for harshness and having to adjust base idle??

Before I pull the Cam cover and front covers etc., to check his timing....is there anything else I could be missing, or could check?
Your thoughts would be much appreciated.
Cheers,
Jim

[pdsman53]

Hi,
I just remembered that I had the Injectors professionally cleaned....they were pretty cruddy.
I'm wondering now if the TPS needs recalibrating?
I'll check the voltage to see if it's in Spec., in due course.
Any other checks would be appreciated.
Cheers,
Jim

[93_Clubman]

ran a diagnostic port check and received the following LED 'blinks' (1-long/1-short), (1-lg/4-sh), (1-lg/7-sh), (1-lg/9-sh).
I assume that equates to codes 11, 14, 17, 19 ??
14 appears to be Atmospheric press sensor???
17 appears to be O2 sensor
...but what are 11 and 19?

According to the following (see 'flash type' codes starting half way down): https://erwinsalarda.com/how-to-read-ma ... d-scanner/
11: Intake air temperature (IAT) sensor Wiring, IAT sensor
19: Fuel quantity adjuster position sensor Wiring, fuel quantity adjuster position sensor

is there anything else I could be missing, or could check?

Appreciate yours starts but the following might give you some ideas:
https://forum.miata.net/vb/showthread.php?t=279746
&
http://wiki.miata.net/tiki-index.php?pa ... tart+Guide

[93_Clubman]

It already had been running fine with extractors/O2 sensor relocated, EGR delete, A/C delete, BP5A intake Cam...prior to the teardown.

It's always possible during the teardown and storing of external parts that they could get damaged I suppose (like maybe O2 sensor), but nothing is obvious/apparent.

I ran a diagnostic port check and received the following LED 'blinks'...(1-long/1-short), (1-lg/4-sh), (1-lg/7-sh), (1-lg/9-sh).
I assume that equates to codes 11, 14, 17, 19 ??
14 appears to be Atmospheric press sensor???
17 appears to be O2 sensor

I tested the O2 sensor, which appears to be working fine...
Ran engine until Hot...multimeter on the connector Signal side showed 0.9+ volts and dropped quickly after switching engine off.
Heater Cables showed that there is continuity.

Had another look at this after having got a few other things done - appreciate the O2 sensor appears to have tested ok, but from what you describe, & given they are effectively a consumable, it sounds like the O2 sensor needs replacing. Try disconnecting the O2 sensor & running the motor from cold to operating temp to see what variation, if any, there is in idle smoothness.

[pdsman53]

Thanks 93_clubby...I'll give that a go.
man this stuff is frustrating....not sure why it happens, when it's a "simple" bolt back together...when prior to rebuild, all ran smoothly.
Cheers