neagan

iTrader: (7)

I know this has been covered in the past, but just in case someone hasn't done it, I had great results from doing it this way.

I've been keeping up with regular use of fuel system cleaner 3x yearly, plus I've taken apart my intake TPI system for a complete scrubbing in the past. Thus I assumed running 3/4 of a can thru my Power Brake vacuum line was most likely a wast. However, there is a remarkable smoothness to the idle that I wasn't aware I was missing!

I should have followed the advice to run this through the intake at night. My IROC belched such a huge cloud of white smoke that my neighbor across the street paniced thinking my car had caught on fire!!!

I keep searching for the reason why my idle fluctuates as much as 600rpm and my fuel mileage stays around 9-10 mpg. I want to figure it out before I switch in my new engine.
Nitro-Nicky

87tpi

iTrader: (5)

I have had great results with seafowm through the intake on all my cars.
Yes, it is better at night or go somewhere in the open because the more carbon and crap you have built up, the more it will smoke. I did it twice on one of my 4runners and it helped it run smoother and the mileage went way up.

fryer1979

That's great, I usually get a few phone calls when I do that to my cars too. I love that stuff though, works awesome.

As far as your idle issue goes, what bases have you covered already? There are a large number of things that could be causing your fluctuation.

urbanhunter44

iTrader: (3)

yeah i did this to my honda beater the other day.. got a good laugh smoking out the whole street

Cadillac

So what's the procedure on a TBI?

87tpi

iTrader: (5)

just slowly pour it into the throttlebody until it dies. let it sit for 15 minutes, then start it up and watch it smoke. i took mine for a heavy drive too and blew all the crap out.

Cadillac

Easy. I ran a couple bottles of Seafoam through the gas tank when I first got the car, I guess this is a lot the same 'cept maybe not a harsh.

You well, Steve?

neagan

iTrader: (7)

****The very first thing I did was to eliminate the 9th cold start injector. Then I replaced injectors with the SVO set and had 'em matched. I took the throttle body apart and cleansed it thoroughly. Took apart the entire TPI intake and scoured it. I installed almost all new ignition parts: Taylor Wires/Denso Iridium plugs/ Added MSD-6 box/Checked ignition ignitor and added full brass distributor cap & rotor (havn't installed billit distrib yet). Installed new Idle Control Valve and checked the TPS for correct voltage.

There's another couple sensors I've relplced, but cant think of em for the moment. I did have PROMS4Less build me a chip orented for what I've done.

After all this work you'd think that there wouldn't be any possible way left for the idle to bounce around from 600-1600rpm. I don't seem to have one bit of trouble with any vacuum leakes left and I use 91 octaine. I also have my FPRS set to 47psi.

I havn't made the time to check for inner play from the distributor or checked to see if the timing is moving around.

Alegedly; just before I purchased it, there was an issue with getting it to smog so the entire exhaust system was replaced with a new O2 sensor, full 3'' tubing and a free flow catalytic. Now I'm starting to wonder just how long of a rich condition these 350's can take before buring out the cat & the O2 again. I did just pass Cali Smog last month, but the EGR tested weak. I guess that's gotta be next.
I've got a computor set up right now with MOATES and need to figure out a primer on getting started.

I'm absolutely thrilled to hear any further ideas. I'm not getting an overly strong fuel smell at idle.......
Somebody come and save my ***!!! Nitro

fryer1979

A vacuum leak is just about always my first suspision, you can check yourself by spraying a fog of carb cleaner over vacuum lines, and intake gaskets (all), if the engine stumbles hard when you hit a spot, you have a leak.

Also check all of your electrical connections, there may be a bad connection somewhere, or even a bad ground. Make sure any ground you have added, or has been added is connected directly to metal (paint must be scraped away from painted surfaces). Not trying to throw an instult at you, but just double check to make sure your aftermarket ignition components are correctly installed. I have been doing this for years and I still am on the tech lines a lot. MSD is especially helpful with their products.

Another thing I would suspect is the O2 sensors, usually they will throw an engine code when they malfunction, but I have seen them not sometimes. Especially since you were told they were replaced, you never really know what was actually done by someone else. The cat and exhaust should be fine, it takes years usually to wear those parts out.

Also check out the distributor like you mentioned, and check out the cap, rotor, and wires while you are there. Corrosion on the terminals or cracks in the plastic or silicone lining of wires can cause an irratic idle. Also just double check your plugs for potential fouling.

When did these problems start? Was it after the installation of a certain part? Do you have a check engine light on? If sinple diagnostics don't work for you it may end up worth your time and money to take it to a reputable shop and have them run it on a diagnostic computer system. Sometimes the ECM will throw what is referred to as "soft codes" that do not cause the check engine light to come on. Some one with a Snap-on "modis" or simular diagnostic system could save you a lot of headaches.

Hope I could help a bit.

blacksunshine'91

iTrader: (10)

That is where I'd start. If they didn't install the sensor correctly, it can cause issues like you have. If the sensor isn't tight enough, air can sneak in there and the car will adjust the timing and fuel rates to compensate.

neagan

iTrader: (7)

Thanks guys for the thorough feedback- I am happy with ALL suggestions because sometimes you never know. I've had cars come back from proffesional shops with a plug wire switched.
Interestingly enough, I just found a O2 sensor that someone gave me last year and had been misplaced, so I'll do that first thing this week. All the tune-up oriented parts are the best I could buy and I did find numerous vacuum leaks AFTER I paid a mechanic $$$ to fix a couple I had found (shakes his head)!

I've got a slightly used ACCELL distributor that I'm thinking of stabbing in. I've always had a weird feeling that the original might be bushing worn even though I've never gone back and checked since my initial ignition overhaul. What amazes me is that the seller provided me with an almost perfect SMOG certificate when it had so many little leaks and other sensor issues.

I just replaced all 27 feet of vacuum hoses on a buddies 1988 Isuzu Trooper with 300k miles on it. Idle was set in at near 2600rpm and timing was advanced @ 22 degrees. Hoses were cracked and/or missing and it came with a clear SMOG! Go figure; I thought it was near impossible to cheat the new Dyno emission machines that are directly connected to DMV.

All this stuff has been an issue from the beginning and I started first by correcting the 9th injector. It just keeps being something else. I finally ignored it all last year and concentrated on the suspension replacement and brake upgrades. Probably I should find a local Camaro and do a side by side comparo to see if there's any missing ground straps anywhere.

again, thanks a heck of a lot for the lists of possibilities~ Nitro

koolctk

iTrader: (6)

I had a similar problem with my black 89 GTA. It ended up being a relay sensor for the MAF that bolts to the firewall. After I replaced it with a used one that worked (diagnosed the old one and checked the used replacement with a voltometer), my car idled fine.

neagan

iTrader: (7)

Are you able to share how you identified the relay and tested for it? I'll dig out my Chilton's and see if I can find it.

With as many bad & marginal sensors as I've come across, it's amazing that I never have/had any engine codes pop up! My light works and when I'm actually disconnecting and test a sensor it'll pick up a code. At least when I'm finally done I'll know my IROC inside & out


Okay; in my repair manual I see two MAF relays: one is a power relay & the other is a MAF sensor burn-off relay. Do you remember which one you found? I understand I can check the MAF itself with a voltmeter for high or low airflow....
Nitro

koolctk

iTrader: (6)

The relay was located on the firewall, drivers side, next to two other relays. I believe it was the power relay and not the burn-off relay but I am not entirely sure. I remember I disconnected the relay and applied the two electrodes of the voltometer to two seperate i/o connections. Bennie is the one who pointed the relay out to me and helped me test it. I don't remember which i/o connections to test it on, nor do I remember what the proper voltage should be, but if you do test all possibilities and no voltage registers then you know the relay doesn't work.

Cameron

89RS_82Z

iTrader: (2)

you can run it through a vac line also, i do both the pour in and vac line on mine

neagan

iTrader: (7)

I took the time today to replace the three firewall relay's: MAF Burnoff-MAF Power- Fuel Pump. My old ones wern't testing resistance correctly so I'm assuming they were marginal at best. I am getting the correct voltage at the MAF itself, although it was a major pain to make a plug adapter so I can test it easily from here on out. I hooked it all back up and it seems to run worse.
However, I did pull the CTS and checked the Ohms resistance. It shows 34.4 and a new one shows hardly 1 ohm. I also put it into boiling hot water and the risistance didn't budge much at all. I also double checked for any thrown codes and none are registered. I found my spare O2 sensor so will get that on soon. I'll check in when I get the CTS installed and descreen the MAF. I was surprised to learn that with the screens attatched it's limited to about 530 cubic ft. per minute versus over 700 after the circumcision.
Later, Nitro

UPDATE: Now it runs worse. I would have liked to have named my car 'The Sting'; but I think it's more appropriate to call it 'The Black Beaver' due to it being a major money ho' le....

neagan

iTrader: (7)

I did the 'tap' test on the old MAF today and figured out the sensor is dying like a lung shot. After checking on 'SEARCH' I decided to order one of Micro-Tech's Adjustable MAF's. It won't be here till mid next week. I couldn't find any of the Wells SU-145 in stock anywhere.
Nitro

Dwayne88IROC

I had a similar problem when I first got my 88. My stock distributor had a broken part under the rotor. It's been a long time so i don't remember what the part was called.
It was magnetic so it stuck there. I remember that much.

Stab the new disty if you already have it.

Stephen

iTrader: (12)

I was considering doing Seafoam too, due to my 180,000 miles but....

My idle is steady as a rock.....I still get 17mpg highway.....Plugs are CLEAN.....

Maybe I don't need to do Seafoam?

neagan

iTrader: (7)

Hey Stephen, how'r you doing?

I've cleaned every nook and cranny in my engine and thought for sure it would be a waste of time. The one reason why I went and did it the hard-core way is due to my havn't about run out of options for my changing idle issues. It's not something that would move around every few seconds, but more of a couple minutes or half hour. Therefore with a spotless intake, 3 years of using high detergent oil, all new tune-up parts, I didn't think it would actually run different.
However, there sure was a difference made. the idle did drop some and it was smoother and a more sophisticated blending of idle noise. I don't know how else to describe it. Allegedly, the more smoke that pours out the exhaust, it means that there was more crap internally than thought. Get the camera and VCR recorder out there!

neagan

iTrader: (7)

My new adjustable MAF came in this afternoon and the black beaver runs better than it ever has. The old MAF still works and I'm unaware of how they can degrade over time like worn sparkplugs, but it definitely was acting out worse than my stepsister (speaking of black beavers...).

I just returned from a two hour drive to give the drivetrain a good heat soak so havn't played with the adjustment screw yet. It still seems to burn way to much fuel at idle and although the idle is much steadier and varies less, it still is up near 800rpm. Plus the top end seems weaker than before. I waited to install the replacement O2 sensor so I could measure the difference the MAF replacement made.

Guess it's time to start preping the new engine block for paint & accesories. These L98's might be a bullet proof design, but the electrical sensor & relays sure are Yugo level crap....
Nitro-Nicky