Hello Third Gen Members,
I seem to have come upon a problem with my TBI recently. I am still new to the TBI, and I have read my manual and done some searching on here, but I cannot seem to find out what is going wrong. 2 days ago, I replaced some minor things, air filter, pcv valve, breather element, etc and I was also toying with getting rid of a belt squeal. Well anyway, now the car has a rough idle at start up, the engine stalls at stop lights, and the idle barely hold otherwise. It does fine when on the road but has these problems listed above. I took the air cleaner off to inspect and to me it looks like too much gas is coming out of the injector because you can see it and smell it. There are no adjustments on my TBI that I know of and was wondering if any of you can either assist me or point me in the right direction. I will post a few pics of the TBI.
Thanks,
Lawrence

 

Another pic

 

last 1

 

kinda sounds like a real big vaccum leak to me. I'd check to make sure you didn't knock any big vaccum lines off on accident while you were putting the pcv and breather and such on (check the line going to egr especially as somehow i knocked mine off while doing the same thing). Might want to check for severely dry rotted lines while you are under there too.

Btw if your sure it's fuel related it sounds kinda like the pump going out to me....I'd check for fuel pressure throughout the rpm range and check for any bouncing or fluctuation that shouldn't be there.

 

hello again,
I ran into a neighbor who is a mechanic and he had a minute so I popped my hood and he told me it sounded like I was running on 3 cylinders. I went home and checked for spark on all wires and I was only getting spark on 3? I only removed the cap and rotor to inspect and felt they were still good enough so I just reinstalled them. Now after doing this I am running on 2 cylinders and I am frustrated. I am going to buy a new cap, rotor, and plugs(only 1 month old) tomorrow and see if this helps. If not, what do I do next, ignition coil? I will reply if I can get it going. What is weird is when I am on the highway it still runs strong with no problems, this was happening only at idle?

 

Huh they made a single barrel TBI? well i do know when the PVC vavle sticks closed the engine really runs rough, but smoothens a bit when at higher RPM.

Distributor isnt loose? and the Spark plugs are decently new and gapped right?

Um how does the car start? battery isnt low on volts or anything?

plug wires go to the right cylinder?

Injector may be dirty and not spraying right, and No water in gas by any chance?

Check for vacuum leaks.

Let us know how you are doing..

 

if the plugs wires cap and rotor are new don't replace them that's just a waste of money. If you're only getting fire to 3 cylinders you've got a heck of a problem...... I'd take the air cleaner off and have someone watch your injecters pump some gas while you go through the rpm range to make sure your pump isn't having *issues*.

If it's fine replace the coil pack and see what happens from there (shouldn't cost a lot since msd and accel coils are only like 45$).

 

You actually managed to get the cap of an iron duke? I heard that was the biggest PITA.

Id check to make sure all the spark plug wires are secure, in good shape, and going to the correct terminals. After that, check to make sure the PCV vavle closes properly at high vac. You can check this by removing it and placing your finger over the end. If the engine suddenly runs better, then you know that the PCV is letting excessive air through.

 

Hey Lawrence,

I'm having the same trouble...minus the spark issue (at least i think so). My car has been running a bit rough at idle and even has a rich smell to it. It actually died on me Monday and I couldn't get it started again do to flooding.

Later that day I got it running again and drove it home with ZERO problem. I had the car running and I noticed the injector was throwing out some serious fuel. I figured it was bad and I spent the majority of my night last night replacing the fuel injector and I threw in a new fuel filter while I was at it.

I started the car back up and it seemed to be throwing out the same amount of fuel as it did before. Again it smelled like it was running rich. It didn't have a real rough idle.

My question is, how much fuel is supposed to be flowing out of the injector? A mist? A fountain? a full open garden hose? I would say mine was like a fountain flowing out of it.


Whats a PVC and where is it located? I'm not getting as good of gas mileage as I should and the car has seemingly been running "off" lately. I replaced the O2 sensor and air filter this past month as well.

Any help would be GREATLY appreciated.

-bill

 

Hello Bill,
The PVC valve is in a rubber boot on the top of the valve cover and it is closer to the front of the vehicle. Tha cap on my vehicle is easy to replace because I don't have AC or anything else in the way. Bill, it looked like I was getting a fountain of gas also in idle, it seems excessive and it smells terrible. I replaced the plugs and wires about two months ago, and the cap and rotor was replaced? I am just going to give it a shot to see if thats the problem for now. Wish me luck and I will post later tonight if the rain lets up and I can get it running.
Lawrence

 

The excessive fuel is due to a high MAP signal to the ECM. Depending on the equipment, it could be due to a severe vac leak, leaking EGR (causes the symptoms above, runs ok, but has bad idle), or a bad MAP sensor. Thinking back, the PCV is less likely as this would be similar to opening the throttle with SD. It would cause a high idle. The EGR is definatly suspect if the problem only appears at idle and is sporatic. The valve can be blocked open by coke, causing a lousy idle.

 

Well, I have some good news. My cap was the cause of the spark and idle problem. It seems as though when I took it off to inspect the middle nipple broke off the cap and thus no spark. i went ahead and replaced the cap, rotor and the plugs again, idle problem solved(WHEW). I also went ahead and installed a new O2 sensor and got a $10 rebate from Bosh. Now as far as the overflow of gas goes, where do I begin? Do they sell these parts, what and how do I check the suspect parts, and how much gas should be flowing from the injector at idle. Like I stated earlier I have no adjustment on the TBI system, and I am new to this type of system.
Thanks,
Lawrence