motor likes running rich? misfire/bogging problem

boostedeh2 · Post by **boostedeh2** » Mon Jun 09, 2008 2:51 am

I've been trying to figure out this problem for a long time now but just can't seem to fix it. The problem is the car likes to run really rich in vacuum. At cruising/in vacuum I have to leave the afr around 11s, as soon as I lean it out to about anything greater than 12.3afr the car will start to bog/misfire. I've tried starting a few different maps, tried switching wideband, different combinations of injector offset/overall fuel trim but still no luck. Earlier I went to take off my dizzy cap and notice that the rotor has some play to it, I will try switching out the dizzy as soon as I get my hand on one...In the mean time if anyone got any suggestions/ advice would be much appreciated! Thanks Here's my setup: D16z6 Vitara pistons Eagle Rods Walbro 255 Precision 880s B&M fpr Bkr7e gapped at .28 Report this post

Bindegal · Post by **Bindegal** » Mon Jun 09, 2008 3:40 am

Maybe this is related to injector latency? When injector duration is less than x.x ms it wonÂ´t fire. What do you use the FPR for? Stock fuel pressure should be fine in 90% of applications. I have seen this exact behaviour before on an AEM managed car with p&h injectors and injector driver box. It was as if the minimum possible injector duration was \"too rich\" and therefore it couldnÂ´t be leaned out without stumbling and dying on itself. /Allan

boostedeh2 · Post by **boostedeh2** » Mon Jun 09, 2008 5:18 am

Bindegal wrote:Maybe this is related to injector latency? When injector duration is less than x.x ms it wonÂ´t fire. What do you use the FPR for? Stock fuel pressure should be fine in 90% of applications. I have seen this exact behaviour before on an AEM managed car with p&h injectors and injector driver box. It was as if the minimum possible injector duration was "too rich" and therefore it couldnÂ´t be leaned out without stumbling and dying on itself. /Allan

I'm trying to switch back to a stock fpr but can't find out, the vacuum hose is disconnected on the b&m right now. How would I fix the problem with the injectors latency? thanks

Bindegal · Post by **Bindegal** » Mon Jun 09, 2008 9:16 am

If vacuum is disconnected from the fuel regulator, fuel pressure will be higher than normal in idle. This does not help in your current situation. To diagnose this further, I would either replace the FPR with a standard one, or at least verify the actual fuel pressure with a quality gauge. My theory is that your injectors are slightly oversized for your application, combined with a higher than necessary fuel pressure. Or maybe this can be fixed by fine tuning the battery ciompensation table... hard to tell from here. With Crome I usually had a hard with 750ccÂ´s on a B16. With eCtune itÂ´s easy to dial in temperature and voltage corrections, cold/warm, high/low current load etc. /Allan

boostedeh2 · Post by **boostedeh2** » Tue Jun 10, 2008 12:20 am

Thanks for your help! I don't have a fpr gauge, So I guess the fpr screw was tighten in some increasing the fuel pressure so I loosen up the screw all the way for it and now its running like how it should. much much better!