Motown

Spent 25 hours over the course of September 10th, 11th, and today changing my original injectors in my 85 TPI, along with some heater hoses and thermostat.

Background story:

Before I changed my injectors I had a hard miss from one cylinder. After changing plugs (wires were new) it didnt change.

Added fuel injector cleaner to the tank and the problem changed from always hard miss from one cyl to running smooth as glass.

This mean it HAD to be the injectors. Well, I swapped in some 19lb Bosch III and the problem is worse. It barely idles in gear holding the brakes, and a rough idle in park.

Triple checked everything I unplugged/removed and everything is back in its right place.

Please help me before I sell this car. I am frustrated beyond belief.

darbysan

Check for a vacuum leak. It's very easy to have one, especially in the plenum to runner area. Also make sure all the hoses to the plenum are back in place.

Motown

I know for sure the vacuum hoses in the plenum are connected right, but is there a special torque sequence for the runner bolts?

darbysan

I checked my service manual but could not find info on the plenum and runners. It's an old manual, and some pages may be missing. The torque is not high- like 20 Ft Lbs. I know I had to do mine twice to get it right. It's real easy to get the plenum to runner gaskets on the wrong set of runners too. I used some Sensor Safe RTV on the gaskets to help with the seal.

Spray some carb cleaner around while the engine is running. If the idle increases, you've found a leak. May have more than 1.

Motown

darbysan thank you for your help. I will try the carb cleaner trick around all of my runners where they meet at the plenum and lower intake. Hopefully i find a leak.

Come to think of it, the passenger side plenum at the manifold sounded very loud compared to the drivers side. I thought it was my exhaust leak there. You may be onto something about a leak.

I hope youre right.

Motown

No leaks at the plenum. Still runs like crap.

darbysan

Is it possible that you got the runner gaskets on the wrong side? I did this on mine, and I was being very careful. There is one gasket that has a hole in it ( I think for the EGR), and it is very similar to the one on the other side where a cold start valve used to be. But they are not identical. I could hardly get mine to run until I found this little bit of mechanical genius I had introduced.

The other thing to consider is that on mine, I had to change the Injector Constant from 19.11 to 17.8 to get the BLM's in line. It was way too lean otherwise. If you can increase your fuel pressure, that is another way to do it as well.

Motown

I remember that I noticed that the EGR hole was a little off and I switched gaskets and got it right, but I had to remove the plenum because I cross threaded a screw. I am pretty sure I got it back on the right sides though.

I could always remove the plenum and check, its not that hard to do.

And I was under the impression that Bosch III's are plug and play? Now you say that I have to modify the computer tables? Not cool. If I would have known this I wouldnt have changed injectors. Because I dont know how to do that.

darbysan

I have an LT1 cam and headers on mine, so I'm sure the flow rate needed to be higher than stock. I really don't think that this is your issue. I would still bet on a vacuum leak. I was absolutely sure I didn't have a leak on mine, and could barely get it to run. It took me a while to find my issues. Keep searching - you may get lucky and find a cracked hose, etc.

skibum2100

Don't get frustrated...

I installed Bosch III's and still had gremlins to chase, its never completely over.

Go back to basics and reset everything to the factory settings. I mean everything: timing, minimum idle air speed, TPS, reset the IAC.

Do you still have the cold start injector? It may be leaking.

Do you have a scanner or access to one. We may be able to see something new.

Hope this helps.

Motown

Do things like TPS and IAC need to be reset even though I never removed them from the throttle body?

I still have a CSI, and do you mean leaking gas internally or leaking seal causing a vac leak?

I certainly dont have a scanner.

Here is a video of what it is doing. At 44 seconds I drop it into gear. When I do a close up of the tach at around the 2 minute mark, the shaking camera is a result of how bad the idle actually is, also by the tach movements...

http://s58.photobucket.com/albums/g2...t=MOV02231.mp4

skibum2100

I meant that the injector may be leaking fuel internally, loading up at idle.

Have you checked the fuel pressure yet?

Do you have an adjustable fuel pressure regulator?

What is the timing set at?

If you didn't take the IAC off, it should be okay. If you didn't mess with the idle set screw in the TB, then the TPS should be okay. But it doesn't hurt to chick.

If you have a laptop and would like to have a scanner, do a search for WinALDL and follow the directions to build an ALDL cable, download their program, and voila...your own scanner. It is absolutely invaluable sometimes.

Hope this helps.

southbay08

This situation doesn't make sense, feel like something is being missed
Not sure if it is an injector problem, however anything is possible and things do happen. We will be more than happy to re-flow your injectors..no charge. Let me know

Motown

Frank did you check the video I made? Its a few posts up.

Anyways, I tore the intake back out tonight and found some black soot around the EGR port on the plenum gasket on the passenger side with a small scuff on the gasket probably from installing the plenum. I will post a pic of it tomorrow as I am done for the night. Not sure if this is a sign of a leak...

I have to pick up a new set of plenum gaskets anyways as I tore a peg removing one of them.

I also found some small residue from the original gaskets near bolt holes on the runner mating surfaces along with some old residue on the plenum itself. Cleaned that off real good with a razor, not sure if that will make a difference or not, but we will see.

The soot on the gasket has me wondering though. Im hoping I found a clue. Like I said I will post a pic of said gasket tomorrow, let me know what you guys think.

Thanks again for all the replies guys.

Dyno Don

iTrader: (7)

I hate to say this, but I am having the same problem, runs worse and the
o-rings are leaking like crazy.
I am going to have to tear into it again (grrrr).

Motown

How does it run compared to my video?

southbay08

If your orings are leaking from the rail side, then it is an installation or an oring issue. That is the only reason why injectors leak from up top, unless the injectors are too short which as long as they have our adapter will not be. Did you install them into the intake manifold first??? Did you lubricate the upper orings before installing them into the rail? Sometime if they are not slippery enough they can "kinda" fold on themselves or tear once they are in the rail.

fireburdluvr85

let us know when you get the gaskets. i had similar issues earlier but of course i ended up toasting another maf. its never one definite answer for the 'similar" symptoms on our cars unfortunately.

Motown

Heres a couple pics of that gasket. Its the passenger side plenum to runner gasket. The dark spot you see does not come off when you wipe it and you can see a little scuff near the EGR port on the gasket. The dark spot is on both sides of the gasket.

Also, the engine was running for a whole 15 minutes total before I took these gaskets out.

Let me know what you think!

george 88gta

iTrader: (1)

I would say that you werent sealing correctly. I have a tip from one of the Vette TPI guys. They use 3M BLACK ( not the old YELLOW) weatherstrip adhesive to set the TPI gaskets. Remove the plastic pegs, apply a 1/8" bead to the metal parts and to both sides of the gaskets. Let it dry for a few minutes until the adhesive gets tacky, then assemble. I run the bolts down starting at the middle bolts and then work my way to the ends. Of course, I am fighting a vacuum leak as well and have the BOSCH III injectors. Pretty soon I will be able to strip and reasemble a TPI in the dark.

darbysan

I did essentially the same thing, but I used the Grey Sensor Safe RTV. Didn't want to screw up my O2 sensor.

fireburdluvr85

i had more of a leak with a sealant. i do torque them from the inside out tho.

TTOP350

iTrader: (8)

I use pam (yes that pam from the kitchen) or spray on white lithium grease on both sides of my TPI runner gaskets.
If you pay that much for them y not make them re-useable???
And yes the upper set of plenum/runner gaskets are side specific !!
pass side plenum gasket has the slope on the top front and the driver side is strait across the top.

Motown

Installed new plenum gaskets, tightened everything from the middle out, and runs no different that the original post and video. I dont know what else to do. The car is bone stock besides Bosch III injectors from Southbay.

skibum2100

Hi Motown,

Did you ever get a chance to check the fuel pressure?

You could check your cold start injector for leaks. Remove the bolt that holds the injector in, loosen the flare nut holding the injector tube to the fuel rail, and rotate toward the hood (pivoting at the fuel rail), just enough to clear the valve cover. Place a paper towel under the injector and pressurize the fuel rail. If the paper towel gets wet, then you have a leaky injector. I had to remove mine altogether because it was leaking, but that required an upgrade to an '89 prom chip.

You may want to consider upgrading to a heated 3- or 4-wire oxygen sensor. The original design is only a one wire, and it relies on heat from the combustion cycle to operate properly. At extended idle, the 1-wire o2 sensor doesn't warm up enough to work right.

Hope this helps.

Motown

I did not check FP.

I just dont understand how it could be all these things like oxygen sensors fuel pressure regulators and CSI's that could go wrong, when before I changed injectors, I had an intermittent dead cylinder. Sometimes it ran flawless for days! Put new injectors in and I can barely get it to idle. All I touched was the runners and the fuel rail.

To me it seems to be either bad or wrong sized injectors, or a vacuum leak at the plenum.

Well Im sure I have no vac leaks at the plenum so everything points to bad injectors. Im getting sick of ripping off my plenum and runners.

I appreciate everyones help so far.

skibum2100

Yea...it seems pretty daunting at times.

The pressurized fuel is always trying to find the point of least resistance, and escape. Now that you have new fuel injectors, that can hold up to much higher pressures; they don't leak which raises the pressure. At this higher pressure maybe the fuel pressure regulator ruptured, or maybe the CSI can't stand up to the pressure.

Everything is connected and each effects the next.

Hope this helps.

Coolnyjay

It can't hurt to ohm test the new injectors to look for a defective one.
If you have the old injectors you can ohm test those to see if the majority of them were bad. If they were bad then it is possible that the poor flow they provided got along nicely with the degraded 23 year old coil and other electrical components that provide the spark. Ditto on the timing setting as noted by others should be checked. My timing was set low and I raised it to 6 degrees as per specs and the idle got rough. I tested the old Multech injectors and found half were bad. I replaced the injectors with Bosch III's after much research and problem solved. Maybe whoever worked on your car previously set back the timing to compensate for the bad injectors? I know it's a long shot but I experienced it. Here is a you tube video showing how to ohm test the injectors by the guy I bought mine from. This guy knows injectors: http://www.youtube.com/watch?v=_g8PdrT0MCU

Motown

All of my old injectors ohm'd out to 16.5 exactly.

Have not ohm'd the new ones.

Keep in mind my 85 did not come with the Multecs stock but I was told that "all stock injectors in thirdgens are faulty."

southbay08

This has turned into such a nightmare for you. The only way that you are going to be able to rule out an injector issue is to send them in to us and let us put them on the bench. If it is not the injectors then you will know that there is a problem somewhere that is being overlooked or missed.

Motown

What is my deadline to get them to you? Im guessing 30 day warranty? I bought them on the 29th of August.

southbay08

No worries, there is no deadline!

Motown

Good to know. At this point I am hoping it is an injector issue by some freak of nature, because all I did was remove the 15 or so runner bolts, removed the runners, and popped the fuel rail. I did nothing else.

While I appreciate all of the suggestions pertaining to oxygen sensors and installing adjustable fuel pressure regulators, resetting timing, resetting IAC etc, I just dont see how any of that could be possible. The only thing left that could be wrong is the injectors themselves.

If I send mine back, I should put the old ones back in to see what happens. At this point, im that desperate.

Dyno Don

iTrader: (7)

I have installed many sets of your injectors and never had a problem until now.
I changed several o-rings and they stopped leaking. (none were torn)

southbay08

Are the injectors leaking from the rail side???

White93z34

iTrader: (1)

I just don't get the rage for these injectors. they don't fit right, require a custom adapter to fit "right" yet can't use the clips to secure them to the fuel rail and cost $170. I think I spent a whole $20 on my injectors... granted they are used but they are ford 19lb "yellow tops" fit 100% perfect in the fuel rail and intake manifold, and I can still use the clips to secure them to the rail. I know they are a sponsor and all here, but there are other more affordable alternatives.

THAT said. have you tried running your car with the MAF unplugged? I know mine ran so many different kinds of bad with a bad MAF. It happened all of a sudden too. I did a plug/wire change and it would not run right after that. I thought I messed something up spent weeks redoing all my work, resetting TDC. drove me totally mad till i tried running the MAF unplugged.

southbay08

If people want to use the newer style Bosch lll instead of the older style "yellow top",
the only way that the bosch lll's will fit is either with our adapter or with double orings. Besides, the yellow tops are 19lb injectors and can only be used in the 305's.
The yellow tops are shorter than the stock injectors as well, however the only reason why they fit the tpi set up is because you have the ability to use a clip and the bosch lll's do not....you need to talk to bosch about that.

Motown

Heres a little update:

Decided to actually drive the car this afternoon. From a stone cold start, it idles extremely low and dies unless I keep the throttle cracked open.

After a few minutes it idles on its own, but rough. Driving the car on the road and its really no different than before I changed the injectors.

-At cruising speed the car glides along, no bucking, etc.
-At a stop light there is an apparent miss.
-Light acceleration and the whole exhaust system shakes and it kinda struggles.
-Heavy acceleration and the car runs exponentially better the higher the RPMs go.
-Still chirps second gear.

I am beginning to think this was not an injector problem to begin with. Since my old injectors ohmed at 16.5 exactly. But im sure the Bosch III's helped me overall, as there is a noticeable sharper throttle response.

With that being said, the only thing I have not done on the ignition end of the engine is a distributor cap, rotor, wires, and set timing.

I also have a right bank exhaust leak near the manifold that may be hurting my idle.

I am going to change the cap, rotor, and the wires (i already did delco copper plugs) and then get the timing set.

We shall see!

george 88gta

iTrader: (1)

You should get that exhaust leak fixed. That is a potential source of unmetered air to the oxygen sensor. Sensor thinks exhaust gas is lean and the ECM reacts by adding more fuel. Could be the reason why car runs better at higher rpms (requires more fuel).If you can get access to a scanner, you will probably see the BLM reading too high ( over 128) and the injector pulse width around 2 or so (at idle).

Motown

This is the passenger side manifold with the leak, with no o2 sensor on it. Drivers side has the o2.

Or doesnt that matter?

george 88gta

iTrader: (1)

Sorry,incomplete info. If you have the stock exhaust, the right side manifold dumps in to a cross over pipe that can backfeed to the left (drivers) side and affect the oxygen sensor. If you have headers, or some other system that doesnt use the cross over, then my info was wrong. Regardless, you should get the leak fixed. I use those thick copper exhaust manifold gaskets ( Summit, etc) sell them.

Motown

Excellent info, thanks. My manifolds are stock. Ive heard conflicting stories on this website about stock engines having gaskets.

Does the LB9 have manifold gaskets or not? Some say they did, others say they didnt.

george 88gta

iTrader: (1)

I believe that they did not have gaskets when new, just machined surfaces. Over time, the hot gases and corrosion, damage the machined surfaces. So when you reassemble it is a good idea to install the soft copper or aluminum gaskets. They do make standard style gaskets ( Felpro, etc.) but I like the soft metal, gives you a better seal.

Motown

Thanks a lot George. Very good information.

Motown

Today I spent 90 dollars on a cap, rotor, wires and plugs. Installed everything and it still runs just as crappy as when I started this thread. Yes I checked firing order.

So here is the grand total list of things I have changed, and it still barely idles.

-Cap
-Rotor
-Plugs
-Wires
-19lb Bosch III Injectors
-Runner Gaskets

george 88gta

iTrader: (1)

I know this sounds like blasphemy, but if the car is basically stock, now may be a good time to find a reputable shop, or even a dealer. They have the tools required to attempt a decent diagnostic for you. It wont be cheap, but neither is changing parts that dont fix the problem. Certainly will be less expensive than buying the tools and attempting DIY. The first thing I would ask them is if they have a smoke generator for air leaks. Probably one of the best tools out there for leak detection. If you have any engine mods, then I would suggest locating a tuner shop. Remember, some dreams are a nightmare.

Motown

I was thinking myself to take it to a shop. There is nothing else I could think of to do.

The car is stock. At least the car is driveable so I can actually drive it there instead of flatbed it.

george 88gta

iTrader: (1)

Just some FYI, call them first and describe the problem. With cars this old, they may not be able to help you. I was talking with a tech, at the local GM dealership, and he remembers working on cars with points and condensor. Most of the newer techs dont have a clue. No point in wasting money.

burnout88

I have fixed many cars that run like this that "professional" mechanics have given up on. But I have the proper tools and test equipment and the car in front of me. If you were in AZ I would say come on over and we would have it running perfect on a Saturday afternoon.

Coolnyjay

True, you have to find a shop that knows these cars and their problems. I once had an 87 Buick Lesabre t-type that I kept bringing to the dealer and they could never find the problem. Now that I no longer have it I learned that the multec injectors were most likely the problem. The dealer never even mentioned the possibility of these poorly made injectors being the problem. I wonder if this board has a list of mechanics that know 3rd gens on it somewhere?