IROCmonkey

Heh, first off Hi all I havent posted for a looong time.

I am having a problem with my car running rich, can smell the unburnt fuel in the exhaust and fuel economy is down. I am also getting an intermittant ECM code 34 (low MAF voltage). Very intermittant, happens once in a blue moon.

Before you ask, no I have not had a chance to check the MAF voltage and look for vacuum leaks, I am gonna do that as soon as I have time and I am also going to check/replace the PCV valve.

I am leaning towards, a leaky injector causing my rich condition and occasional hard starts. Which I really don't want to deal with

Can bad MAF readings be causing it to run rich? When I do get the code 34 it happens as soon as I fire it, no waiting.

I've already replaced the O2 sensor (it was due) and I replaced the CTS (which actually helped, I think it was bad and the ECM thought the engine was cold, enriching the mixture.)

Opinions and insights?

IROCmonkey

ttt

Daves89GTA

I am having a similar problem, getting a code 34 about 5 seconds after startup, about once every 10-20 starts. Also I noticed a significant increase in unburnt gas out the tailpipe and reduction in fuel economy. Have you been able to figure out what is going on?

My MAF is only about 6 months old, but maybe this is due to bad burn-off relays? Otherwise the car runs okay. Let me know if you solve this.

Vader

The MAF error code will cause the ECM to run in Backup Fuel and Spark Mode. In this mode, the timing advance is negligible, and fuel mixture is quite rich, somewhere near 12.5:1 or 13:1. This is intended to get you to the nearest service facility without risk of going lean and damaging a valve or piston top.

Funny maybe, but when that little yellow light on the dash illuminates, there's usually a reason.

The rich odor is likely related to the MAF error. Since you know that you have to check for MAF connections, output voltage, and vacuum leaks, it would be good to do that first. While checking that MAF output voltage, make sure you check the MAF power at the sensor, just to make sure the relays are working properly.

As for the generation of a MAF error intermittently (every 20 starts) you may have a MAF connection problem, or more likely a MAF power relay that is failing, or a MAF burnoff relay that isn't closing.

IROCmonkey

Basically after it started running even worse, I realised I was having ignition problems, turns out I had burnt and fouled plugs (yeah I know shoulda checked there first thing). Swapped out the plugs, changed back to Syntec Blend from Mobil 1, and ran a can of hi dollar (4 bucks ) fuel injector cleaner through it and its back to running like it did when I installed it nearly 50k miles ago. No smoking, oil consumption, and my gas mileage is back up to 14+ in the city (I have a leadfoot, granny would get better).

On the flip side, I do still get an intermittent MAF code, when I do I just shut it off and restart it, it resets right away. Like Vader said I prolly have a loose connection somewhere, but then don't we all.

Do you only have rich condition when you get a MAF error, or are you running rich all the time. If only when getting the MAF error, then troubleshoot the MAF error. If it runs rich all the time, check over things like O2 sensor, basic ignition (plugs, cap rotor, wires), check your base timing too. Aim at eliminating the rich condition along with checking the MAF voltage and connections.