* NOTE! This is a bit of a long post, so skim ahead if you wish to skip to my technical questions *

Alrighty, I've been busy doing a bit of research this evening, and so far, my findings have me a bit concerned about the overall health of my car's 305!

I've slowly tackled and troubleshooted various issues on the car since owning it, but it still isn't quite in roadworthy condition yet. Due to to the fact the tabs on it expire very soon, and emissions testing is required for renewal while the car is undriveable (not running due to fuel issues, needs brakes bled), I'm sort of in a situation where I'll have to have this thing towed to either a friends property or repair shop, to avoid unwanted trouble w/parking tickets or threats to tow.

Anyways, enough of my situational story, but I feel it's worth mentioning just to point out that I don't have my own workspace for any type of major repairs.

(OK, onto the tech stuff here!)

The engine is the 305 TBI/L03. The car has never ran quite right since owning it, as it's had random misfires at operating temp (idle only), check engine lights coming on w/noticeable loss of power (ONLY when the light is on), and ran pig rich. The car also showed signs of bad valve seals (small blue smoke cloud on start-up in mild weather that went away after) The car has mostly spent time parked for the last year, but periodically ran/worked on too. However, the running issues persisted, even after many basic part replacements, which include the following..

Spark plugs
Cap & Rotor
O2 sensor
Coolant temp sensor
EGR valve
PCV valve
Air filter
Running the car w/seafoam
Radiator
Water pump
Heater core

There's other parts (non-engine related)/others I may be forgetting, but overall, last time the car was running (force-started last week), it was running pretty rich, and slightly rough still. Not much better than when I bought it. However, oil pressure has always been good at least.

Reading another topic on here, and other sources regarding emissions, and what the numbers mean, I decided to look for my old test results back when I got the car. Keep in mind that at this time, the car was as-is. No new parts had been installed.

HC (PPM) Cruise Limit: 150
HC (PPM) Emission output: 1875(!!!)

CO% Cruise limit: 1.00
CO% Cruise Emission: 1.92

Based on what I've read, extremely high HC numbers often indicate engine misfires and poor oil control, and that high CO = running too rich, though they can mean other problems too.

A couple of easy to get to plugs I pulled out once revealed some carbon fouling, and possibly traces of oil. The last step I'm at short of checking every plug is (and something that might as well be done) an all-out compression test.

Finally, I guess what I'm getting to is that over 12 times the legal HC limit has me a bit concerned. Does this sound like a motor that's probably in need of overhaul? I realize I should still do a full compression check too, but I'm a bit concerned at this point, and do not want to waste too much money fixing a 305 if it's at the end of it's useful service life.

P.S: The odometer has about 156K on it.

 

Have you got new plug wires yet? It goes along with cap & rotor/ plugs, but you didnt list it above so i had to ask. If not, this may help with the misfires, if not it should at least help smooth out the idle and make it run a little smoother.

Have you checked the fuel pressure? Had fuel filter replaced?

Ohmed out fuel injectors?

Checked TPS for right adjustment, working correctly?

IACV? MAF? MAT?

Checked for any vacuum leaks?

When it has the SES light on, have you ran the codes? Thats always a good idea, it will help guide you to the right solution(s).

Just out of curiousity, when you seafoamed the car, how did you do it? Thru EVERY system? (fuel, oil, PCV/vac lines, maybe even use TB cleaner on it?)

It sounds like you have replaced a few things that could be causing the problem(s), so your off to a good start. Try these, hopefully something will point you in the right direction. I would defenitly start by running those codes tho, its very easy to do, only takes a couple minutes, and will be very helpful.

 

Hey there, I'll answer all these in order of posting!

No new wires, however, it was in mind at the time of the plug and cap/rotor replacement. I basically decided to see if those two would do the trick at getting it to run right first, but obviously, it didn't . The next night, the car overheated, and that's when it went into it's current state of "mostly parked" mode.

Fuel filter was replaced back when the car was in active use, so a year-ish ago. Fuel pressure was next on my list, but at the moment, I don't have a gauge to check it myself, and my main priority is getting the car onto private property before the tabs expire before I continue w/repairs.

No ohm test on the injectors. Got the car to run for a few minutes last week by pouring a small amount of gas into the TBI, but it died after that. Would the injectors have to be working for it to run for a few min?

TPS hasn't been checked

IACV/MAF/MAT are other suspect spots that still need checking, but I wanted to get trouble codes before I just throw money at random parts in hopes of lucking out.

As far as vacuum leaks go, that's actually something pretty important I forgot to mention among everything. When I was changed my brake master cylinder, I noticed what looked like a missing intake manifold bolt, or something for the TBI, which has me thinking that could be causing major issues.

I haven't checked for codes, because I didn't know how to before. Any trouble codes were erased when I disconnected the battery doing other repair work. When I tried driving the car again to try and get trouble codes to come back - surprise! brakes are shot. That was my most recent work. Now that it's time to bleed 'em, it's not starting, go figure!

Seafoam was ran through the gas tank. Not entirely sure how much it helped, since the car overheated shortly after.

 

Hey, i completely understand what you mean about getting it to private property, i had the same problem not too long ago.

If plug wires havent been done, it really shouuld be. It probably wont fix EVERY problem your having, but it will definetly help, and could very easily fix your misfire problem.

Fuel pressure definetly should be checked, once you've got the time to check it.

As for the injectors, thats a good question. The injectors need to be tested cold AND hot, so once before the car is started and again after its warmed up. If the car wont warm up completely before dieing, check them immediatly after it dies. If you dont know how to do this look it up on youtube, theres alot of helpful videos on there about this. Its not hard, and you could have 1 or more leaky injectors. (especially if theyr the original stock ones, they just suck. Very bad design.)

Also, the TPS could be causing this. My car ran great while cold, but once it started warming up it was a mess. No power and always would stall. I checked the TPS and it was way off, after fixing this it runs like a champ. I consider myself lucky thats all it was, but hopefully you'll be as lucky as i was. It should be set at .54V (i set mine at .545 if that helps any). Again, if your not positive how to do this theres vids on utube, thats actually where i learned how to do it. Thers a guy with a 350TPI formula on there, yours can be checked the same.

IACV, MAF, MAT, can be checked. You dont have to buy new ones to figure out if they were the problem.

The missing manifold bolt, that could absolutly be the problem. Spray some starting fluid/carb cleaner, TB cleaner, ect on the area of the missing bolt while its running. If it affects the idle any at all, you have a vacuum leak. Chances are you have a monster vac leak there.

also, you dont have to drive the car for the codes to come back, it usually only needs to run for a couple min. Sometimes they come back immediatly. Someone on here sent me a very useful video on how to read our codes with just a paperclip, PM me your email and ill forward it to you. It only takes a couple min and a paperclip.

Seafoam in the tanks a good start, but to really get a big response you need to run it thru every system. The PCV is usually the biggest game changer. If you have a vac leak and run it thru t he PCV, it usually will start smoking (like it does from the exhaust) at the point of the vac leak. I had this happen to me, it made it simple to find my leak. When u get it running you should definetly do this.

Hope this helps!

 

Ok, I'm back with an update!

I decided to get some help from a mechanic friend of mine. Had the car towed up to his shop, and he did some work to get the car running again since it was in a no-start condition I thought was fuel related. Turns out that it wasn't fuel related. Turned out bad ignition coil wires were the cause of that. Also gave a set of new plug wires a try, as it turned out several of the old ones, were in fact bad!

The good news so far: The new wires, although not getting it back to running perfect, made a noticeable improvement in the idle and it didn't surge at all. I was told the fuel system was ok-go. And also, a n00b mistake on my part, turns out what I thought was a missing intake manifold bolt, isn't

The bad news: Although it's idling smoother, it still misses a bit at certain RPM's, most noticeably under light throttle. But not at all in mid-throttle. And hopefully, I just didn't properly tighten my heater core hose clamps, otherwise, the replacement heater core I installed a bit back is no bueno (There's a leak somehow), and I have a hell of hassle to deal with again. Also, noisy rattles from the exhaust heat shield have gotten more annoying

At this point, I think it's time to remove every spark plug and see if they continue to foul.

 

Did you replace the spark plugs too when you replaced the coil and wires?

As for the miss, i have to say this just because i want to make sure this ISNT the problem- all TBI's are known for having a "bogg" at lower rpms. My car is tpi,so i dont know this from experience, rather from reading and talking to people that have TBIs. TBIs apparently all have a slight "miss" or bogging down" problem, and primarily at low rpms, like you said yours is. Im not sure how much you drove the car before, and if you have ever driven it when its running correctly, so the "miss" MAY just be how that car is- in other words, normal for your car. (Ive always heard this: TBI=Tough but Inadeqeute.) I wouldnt be surprised if thats all it is honestly.

It is a good idea to check the plugs again, they can tell you alot about your engine. Another thing worth mentioning, did you check them for proper gap before installing them?

Also, if you havent already, check over all vacuum lines for any cracks, splits, or any lines that look old and brittle, and replace them if you come across any.

And now that its back to running condition, you should defenitly try the proper seafoam treatment. This can help clear up misses if there are any. The vacuum lines are often forgotten, and are very important, so make sure to do them! Vacuum leaks can cause a miss too, so again, the seafoam can help you find any too. When i seafoamed my car, this is what made the biggest difference of them all.

Seafoams website has a list of ways to do the treatment, itd be a good idea to check it out.