LongDuck

First off, I'm new to the forum, but have been lurking for about 3 weeks before registering. I've gathered some great information from your posts about fuel injector size, capacity, and troubleshooting, but have not been able to figure out an idle problem that I'm still working with. Any help appreciated;

The car - 1984 GSL-SE w/EFI, no internal mods, stock exhaust save for the RB PP muffler and K&N filter. 162k mi on original engine, AZ car, low humidity, high heat.

The initial problem - gasoline smell from engine bay after driving, traced to fuel injector for rotor #2 (rear), injector plastic body leaking, dripping fuel onto intake manifold.

The solution - replaced rear injector with factory rebuilt from BAP, reseal kit for both injectors due to hard rubber o-rings and seals, reinstalled intake and all vacuum lines.

The continuing problem - car does not idle smoothly and had to bump up the idle to 1100rpm just to stay running. Very lumpy idle and engine is visibly shaking in the engine mounts. Acceleration off idle is poor, seems to be running rich. Once engine gets above 2000 rpm, then seems to run better, but still off on power throughout entire range.

What I've done - doublechecked the vacuum lines, checked pulsation damper, checked plug wires, replaced plugs (NGK BR8EQ-14's, but old plugs were slightly carboned, not fouled).

The leaky injector ran just fine and the engine was smooth, so I'm thinking of putting it back in just to see if it all smooths out again. Any suggestions? TIA,

JEC-31

While the thought of risking fire and death by intentionally putting the leaker back in kinda scares me, it's a fairly sure way to see if you got sold a badly redone or wrongly sized injector. Get a couple of fire extinguishers and a lucky rabbit's foot and go for it.

The fact that it ran fine with the leaker does point in that direction.

Directfreak

iTrader: (2)

1st off - Welcome.

2nd - Did you only replace the ONE injector? If you did, that could be the problem, as they really should both be a true pair. Kinda like when replacing tires, always in pairs. The newer injector might have a slight impedeance difference from the stock one

3rd - Since you obviously removed the manifolds to change the injectors, - they might not be sealing as well when you put them back on. Try spraying Carb cleaner around the manifolds connecting points and see if the idle changes - it will help you locate any manifold leaks.

4) Some people (myself NOT included) have advised that if your O2 sensor goes bad, that it affects fuel economy and idling. - just a shot.

If that doesn't work, there are several well written pieces on solving GSL-SE idle problems, but if you haven't messed with the MAF, TPS, or idle screws, so I doubt that may be your problem.

LongDuck

Thanks for the quick replies. I only changed the injector that was leaking, since the previous owner changed the *other* injector that was leaking about 4 years ago. At that time, the single injector was changed, and the car ran well, so I wasn't too concerned.

As it stands now, I will be taking the old injector (replaces 4 years ago), and the core from the recent replacement and sending them both off to INJECTOR.COM to have him rebuild, flow balance, and leak test them both. This should help in performance down the road, but mostly I'm just trying to limp along until I can get these 2 rebuilt and back in my hands to install.

I'll definitely try putting the old, leaking, injector back in tonight to see if the idle smooths out. If so, then it's a gimme that the injector is either the wrong part or was rebuilt poorly. Will report back with results. While I'm in there, I'll also use carb cleaner to see if my manifold gaskets are leaking and take another look at the vacuum lines under there.

From removing lines and checking pressures last night, I could be talked into this being a vacuum leak, but since it was running fine before the injector swap, I'm still thinking it's the injector.

Hopefully, I won't have a new thread up tomorrow about "My car burned to the ground!!"... Thanks,

LongDuck

As an update - when out driving yesterday, I had a problem whereby the car sat for 10 minutes while I was in a store, came out, and when started was running REALLY roughly. I mean single-rotor operation.

When pressing on the accelerator, the engine was extremely sluggish and exhaust sounded very 'thumpy' for lack of a better word. Power was less than half normal, and the car was barely driveable. I think this supports my belief that I have a bad fuel injector, i.e., it quit and that rotor was running without fuel, but wanted to get other user's opinions about this.

During a search, I found a thread on 'running on single rotor' and this was due to a bad BCAV valve on the side of the EFI, but could also have been related to injectors.

I plan to swap out what I believe to be the bad injector for the 'leaker' tonight to be sure, and will report back when able. Unfortunately, the coolant gets too hot to remove the upper intake manifold with the thermowax leads from the water pump.

Open to any suggestions you guys might have, and thanks for the help,

gump

Have you tried this one??? Other then the injectors it seems to be the most sensible problem you may have. I mean, you did say that it was running fine before you swapped the injectors, so you'd think it would be the injectors or something that didn't go back together the way it should (manifold leaks, etc). Good luck.

MRGSL-SE

You know that I think about it, You did say you replaced the thermowax hoses on your GSL-SE, that crossed out that problem. I agree with Gump (person before me) that the manifold could be leaking. I think thats also in my case, except without the stumbling.

I've done this a lot just to check what would happen, remove the skinny vacuum hose that leads to the BCAV your engine should stumble and I think thats how you check if its good or not.

I'm gonna do that too on my gsl-se, put some carb cleaner... just chippin in after all the suggestion you've givin me... thanks

Marques

LongDuck

Yep, tried the carb cleaner around all the vacuum lines and the BCAV and the manifold attachment points. When I put the manifold back together (upper to lower), I made sure to get the new gasket from a local Mazda dealer. The old gasket was the original and fell to pieces when the manifolds were separated. I was thinking that maybe this new gasket was compressing, so gave a few more turns of the wrench to be sure it was down tight. Very little room to tighten it down.

No idle changes with spraying the carb cleaner around, so I don't think it's a vacuum leak afterall. I also noted that at steady-state driving conditions, the car surges forward and back, which is pretty indicative of an injector problem, i.e., not flowing consistently.

I've had BAP order another injector for me and it should be in on Friday. At this time, I'll replace the recently rebuilt one with the newly received one, and we'll know for sure whether it was just a bad rebuild.

In the meantime, I plan to send my 2 old injectors (spares) off to Injectors.com to have them rebuilt, flow balanced, and leak tested. These will likely go back into the car, since I'll know they're volume matched.

Thanks for the help, guys.