TonysBird

Ok so it started this morning before I was going to get the emissions done, of course, the engine is running rough and shaking but the amount of shaking stays the same no matter how much throttle (the frequency of the shakes changes with the RPMs evenly). It's also lacking in power a bit and it doesn't feel like it's going to stall. I initially thought it was a misfire caused by the bosh platinum 4s but I swapped them out with AC Delcos and it still has the problem. It has fairly new wires, cap, rotor, coil, and icm so I don't believe it's an ignition problem. I'm thinking it could be one or more of the fuel injectors but any input would be much appreciated.

Also I have a data log that I ran with TunerPro if you guys would like to have a look..

TonysBird

**Update** I decided to drive it an hour to work today and it still has that strange even stumble issue that appears to get worse once the car gets hot. Though it is less noticable while cruising on the highway but if I give it gas it hesitates slightly then the stumbling becomes more prevalent while accelerating until i let off the gas. Also, when I got into town it was stumbling quite a bit and kind of sounded like it had an exhaust leak (which I will check the exhaust this evening) along with the lack of power issue.

I did a couple hours of searching the forum and have not really found anything conclusive, though I still believe it to be the fuel injectors or possibly the fuel pressure regulator? I'm used to dealing with carbureted vehicles so I'm sort of lost with this FI issue. Any input would be greatly appreciated since this is currently my main mode of transportation..

TonysBird

Well after more hours of searching on here I decided to check a few things.. I ohmed the injectors and they all seem to be fine and the FPR vacuum line has no smell of gas. I also checked my TPS on tunerpro and it seems to be operating properly as well. Tomorrow evening I will double check the ignition system to rule that out for sure, and I will check for vacuum leaks. That's pretty much all I can think of so some input would be appreciated.. I have to move here in a couple days and would like to get this issue sorted out asap..

P.S. I attached a short data log with me idling and a rev while the issue was most prominent if you guys could have a look..

TonysBird

Kinda of surprised at the lack of responses but I'll keep updating to help out anyone else who has this issue.. Anyway I ran it through emissions and failed with high-ish NOx numbers but everything else was better than normal. From the research I've done that means either my EGR is bad or my timing is off (though I don't know how the latter could have happened).

**edit** added smog sheet pic

TonysBird

It's been over a month and I finally got time to run some more diagnostics. I checked the timing which was only off by a degree so I fixed that. I also went through and rechecked ignition by pulling one lead at a time from the distributor cap. Only the cylinders on the odd side were affected, the even cylinders showed no difference with the leads pulled. So that means I have a serious miss issue... The odd part is that I replaced all the plugs after this issue first developed and there was no change.. I guess next I will test for spark at each plug on the even side and see where that leads me..

TonysBird

Well I Ohmed out my injectors the other day and all of them were within a range of 16.6 to 16.4 hot and cold.. I could really use some advice from those of you who are more experienced with this kind of thing..

rutters27

a stuck open egr will make your 305 miss

TonysBird

Hmm yeah I have not checked that yet but one thing I found odd is that one half of the engine is getting combustion.. So i've pretty much got a slant four right now haha

rutters27

passenger side running rough ? thats the side that would more than likely be affected most by a stuck egr sincr thats where it is they are a bi*** to get off try spraying it with some goood penetrating oil and bumping it around with a hammer (yeah krog use big poundy thing) dont take my advice as the word im no ace mechanic but ive never met one that i couldnt make run or try hooking it to direct vacum and rev the engine a bit while watching the egr you should be able to see it move or be able to put your finger up inside the dome part and move the diaphram a little it should move stuck shut makes no difference maybe an idiot light at most but stuck open will definetlly cause a miss its like having a 1/2 inch hole in your intake do you have a check engine light and is it on if so

TonysBird

Alright tomorrow evening I will run these diagnostics and report back with my findings. Thanks a lot!

rutters27

if you have spark on that side and you certianly have fuel unless your intake is clogged which i doubt because the rest of the engine runs then its the air fuel ratio too much air IE stuck egr or intake gasket is shot on that side or worst case is head or cam problems any rattles or smoke does the exhaust seem rich but if you have spark at the plug id start with the egr there isnt much to them dont be ascared to tear it off and clean it up if you can turn a wrench you can do it and after 100xxx miles they carbon up pretty good on most cars do you have the stainless tubes off of the exhaust manifolds if you do and the egr is carboned open those tubes are doing nothing they will be plugged totally shut with carbon this never made sense to me made of stainless so they last forever but are so small inside diameter they just carbon shut after a few years what were you thinking GM i dont have these issues any more tubes pump and egr are gone but i run classic plates so emissions are not an issue

TonysBird

The engine sounds and runs like it has a large misfire and at initial start up it does puff white smoke but it runs only slightly rich at idle (not enough to see in exhaust). Oh and the service engine soon light is not on but it does work.

Jhook

iTrader: (2)

You can try replacing the EGR valve, injectors, or Idle Air Control Valve. My camaro had a very similar problem, you could drive it, it would misfire, run rough, hard start/ rough start, and would die sometimes at idle. After taking care of the idle air control valve and te EGR, it smoothed out some but the injectors were clogged up which resulted in half the cylinders not running at 100%. After replacing the 8, car runs great. Id make sure its the injectors having problems first though..they arent the cheapest thing to replace if you have to do all 8. A good sign is a running rich/ running lean in certain cylinders

92w-68

have you been able to narrow the problem down? i have a 92 firebird tbi 305 that is having a similar issue i have been trying to figure out since around may haha so i have been letting it sit now its time to finish it up and move to a new project, anyway it starts up idles at like 1800 and only revs to about 2800 and misfires so this last week i have been reading how a faulty map sensor affects the car and the egr as well

Mr Froman

Injectors may be within spec., but how is the signal to the injectors?

Unplug and check for injector pulse with engine running. Use noid lights.

If all is fine, use a spark tester. Check for spark. If all STILL is okay, tap your EGR. Change in idle quality? Also check vacuum. A stuck open EGR is basically the same as a vacuum leak. What I do to help break down carbon in my car and customer vehicles is a throttle body service. I clean the throttle plate with cleaner. Than I start the car. Insert red tube from can of TB cleaner through air duct. Allow a little bit of cleaner in at a time. Engine will stumble. This basically helps break down some carbon build up.

An entire bank misfiring is strange though. If anything else I said doesn't help, perform a compression test.

TonysBird

Well I replaced the EGR and the issue didn't change at all and I tested the vacuum and spark, it all seems fine. Next I will retest the injectors but more thoroughly this time. I'm pretty stumped by the fact that the one bank is malfunctioning..

TTOP350

iTrader: (8)

Check your 2 INJ fuses under the dash.
If thats not it, use a noid light to check and make sure your getting voltage to both sides of your inj harness..
You could have a bad inj driver in your ECM, you only have 2, one for each bank.

TonysBird

I tested for voltage all around and the injectors on the good side receive the appropriate amount along with a good solid pulse. The other side is receiving voltage but they are not pulsing (voltage does not alternate from 0-13v but stays constant). This leads me to the believe that the injector driver ECM has gone bad..

afremont

Sounds like something is wrong on one side. Before you replace your ECM verify that the "grounding" side of the injector harness has a good wire all the way to the ECM and that it is not cut/open somewhere. I'm not saying it's not the ECM, but the driver transistors have pretty good protection that will shut them down if an overload/short occurs. Also unplug all four injectors on that bank and try a noid light in just one of them just to make sure you don't have an injector that's shorting intermittently.

TonysBird

**Update**
I know it's been quite a while since my last one but I've finally got back around to figuring out the issue. After running tests with a noid light all eight injectors were pulsing fine so I decided to pick up a new set of injectors. During the swap I discovered that the injectors and fuel rail on the bad side were terribly gunked up and half of the fuel pressure regulator was as well. After cleaning the gunk out there was quite a bit of corrosion and pitting, to the point to where the sealing surfaces in the rail were no longer usable. I believe I may have finally solved the issue and am now awaiting a new rail..