erockwell

I’ll try again when I get home, but yesterday when I tried to adjust it, the readout stayed at +20 no matter which way I turned the distributor, and I used the idle adjustment screw to keep it at right about 1200 rpm. What could be causing this issue?

Okay. So I installed the new billet aluminum distributor (42 bucks on amazon, but had no reference marks so it was kind of a pain), verified it was working, cleared the codes, and drove around for a while. Coming on the heels of the MFI upgrade I just did, the truck has never run better. The weird thing is that the CMP offset still hovers between +18 and +20 degrees, and rotating the distributor has no effect. I have no idea what’s causing this, and while I’m thankful that the truck is running like it should, I want everything to be dialed in perfectly due to all the time and effort I’ve put into it. Thanks a lot. I don’t think I could have gotten this far on my own.

Well I think I found the problem. According to the scanner, it reads +31° at 2000 RPM. Hooked everything up in the parking garage when I left work, and I’m going to install the new distributor and set everything up as soon as I get home.

Well that’s interesting for a couple reasons. I was checking out the app and I found the timing section, which had a readout in degrees, and I thought that was what I needed to refer to. I also looked into buying the PIDs for my truck and the app said there weren’t any available. My scanner is arriving today. Is this something I can only access once the scanner is connected? I’ll be starting the operation today and will update with any issues. Also, is there an easy way to verify that the engine is at TDC on the compression stroke before I put the distributor in? I saw a video that mentioned it’s easy to accidentally put it in while it’s at TDC on the intake stroke and I want to make sure I have everything just right.

Thanks for the excellent advice! No, I haven’t done the fuel filter yet but that’s a good suggestion and I’m going to that ASAP. I just replaced the spark plugs and several of them were fouled. Although that helped with the hesitation, it didn’t eliminate it entirely. The idle is much smoother and the acceleration is improved, but I don’t think it’s 100% fixed yet. I believe what you said about the distributor seems very likely to be the issue, so I’m going to shop around for a good new one. I really don’t want to break the bank but at the same time I don’t want to get a piece of junk, so I may post some possibilities on here to see what you think. I looked into the dashcommand app and it looks really cool, but I couldn’t find much info about compatible scanners. I looked on Amazon and found wireless OBD2 scanners ranging in price from 10-300 bucks, and once again while I don’t want to get a cheap one I don’t want to pay a premium either. If you know of any decent ones for between 50 and 100 bucks, that’s what I’m prepared to spend on a scanner. Thanks again for the advice. EDIT: I found a Bluetooth enabled scanner on Amazon that’s compatible with Dashcommand and had good reviews for $30. Should arrive Tuesday. Already downloaded the app. I’ll know more and will be able to post more information once the scanner arrives. EDIT #2: I replaced the fuel filter and cleaned the MAF sensor today and that didn’t seem to do much. I also determined that the throttle position sensor is bad (no change in engine performance when I unplugged it) so I went ahead and ordered a replacement. I also ordered an inexpensive distributor with decent reviews. It’s made of aluminum at least. I only ordered it to get me through until I can afford a good one. It will also give me a chance to get the hang of adjusting the ignition timing.

I'm having a bit of a dilemma here. I have a 98 Yukon and back in January it started missing. I replaced the plugs, wires, cap, and rotor, and it worked fine for a while. A few weeks ago, it started missing again, this time much worse. I replaced the O2 sensors and that didn't fix it, so I took it to the dealership to have it diagnosed. The dealership said that the distributor and the injectors were bad. I replaced the distributor with one from a salvage yard, and upgraded the old spider to a brand new AC Delco MFI injector system. I just finished replacing the injectors yesterday morning. I cleared the codes and took it for a drive. It all seemed fine, but then I noticed a slight hesitation and sure enough it showed the same misfire code. At this point I feel like I've done everything I can. When I put the intake back together I noticed a few things. One is that one of the screw holes on the new distributor is stripped, and wouldn't tighten down all the way, so I'm wondering if a slightly loose cap could be having an effect, and I'm also wondering if the plugs could have gotten messed up while the engine was missing really badly and if I should replace them again. I didn't replace the MAF senor when I did the O2 sensors, and I'm wondering if I should have, and I'm also wondering if I should take out the salvaged distributor and replace it with a new one. I found a good deal on one through Amazon. Knowing all that, is there anything else that could be causing this slight hesitation after all the work I've already done? Thanks in advance, Eric