85C4fanatic

No problem dont think twice. I have had others help me in the past and feel like I need to lend a hand whenever I feel I have enough experience in teh topic. I dont think that just grounding the ALDL pins will tell if you are rich or lean. I used winAlDl for my 85 for a datalogger. Cable is really easy to make if you cant make one I can refer you to someone who only charges 25 dollars for a cable. Then you just download winAlDl and if it is new laptop chances are you'll need a usb to serial converter. But then you can log sensors, TPS, IAT, BLM knock counts, you name it. Do you know anyone near you with a similar car that you can borrow the ECU from to test to see if it is the Puter?

rick lambert

I think RRT already posted about checking lean/rich mixtures using the field service mode, difference in flashes, although I don't know how accurate it is. If your afraid of checking certain areas for vac. leaks because of fire concerns....use an UNLIT propane canister with a torch head (soldering, whatever). There are vac. lines under the plenum that need to be checked.

davemack

Thanks again, Rick. RRT did tell me to check for rich or lean condition by grounding ALDL. After seeing his post, I looked it up in the FSM as well. Only problem is, neither tell me exactly which terminals should be grounded and when (maybe just jumping A & B terminal grounds it?). That's one thing about the FSM - it's awesome, but assumes you have been trained for a couple of years at a tech school, or at least have some mechanical background and aptitude.

Would you suggest propane over, say, carb cleaner spray? If you tell me there's little to fear in spraying carb cleaner under the plenum in a well ventilated area, I'll do it (but, I'll still keep the fire extinguisher by my side...)

davemack

I'd very much appreciate the info on the person who sell the $25 cable. That's a heck of a bargain, especially if I can download the WinALDL software for free. A $10 adapter at Radioshack and I'm good to go!

I actually bought an ECM from another CF member, Bruce Witherspoon, just in case... I need to buy a prom removal tool before I can install, since Bruce's car is an 85 w/ automatic and mine's a 4+3. I also need to call TJ Wong, another CF member who I'm told sells good prom chips. I'm not sure if he needs the ECM to burn the right chip or just details about the car and it's options. That's another reason I've delayed in putting the new ECM in (besides the fear that accompanies inexperience!)

85C4fanatic

Unless he has a supply of blank memcals you'll have to send him yours. But why do you think you need a new chip burned. What other mods other than injectors do you have? I'll dig the guys name up. He is from another Car Forum.

rick lambert

Same two terminals for field service mode..top 2 on right hand side.
I wouldn't be afraid to use carb cleaner checking for vac. leaks...the fire extinguisher is a safe bet. When you check for vac. leaks don't just check the connections....scan the whole plastic line, especially the curves, many aggravating hours I spent trying to find one, turned out to be the one by the alternator..on the curve.Also, there's an aluminum tube running along the valve cover..drivers side,top side, close to the alternator...spray the end of the tube too.

kopbet89c4

Is your high idle bothering you that much? My car actually idles at 900 or 1000 rpms when first started up. Doesn't bother me that much. I feel like with a higher idle I can get more power off the line, e.g. when racing.

davemack

Mine idles at 900-1000 at start up too, and that doesn't bother me at all. It's the random hunting or surges. Like today, I'm driving the freeway to work, take my exit and begin downshifting as I approach the stoplight, Reach the end and depress the clutch to stop and I'm idling at 1300 rpm, steady as a rock. I drive to the next light, maybe 2 blocks down, now I'm idling at 1300-1400 rpm (switches between the two). I drive about another 2 miles, hit the last light, and I'm idling at 700-730 rpm.

It's also not unusual for me to be idling at around 690-740 rpm, then watch the car bump up as high as 850-900 rpm just for a split second, then ramp back down.

I might have two issues; bad TB bushings and maybe an ECM problem that has the IAC adjusting to phantom changes?

I talked to TJ - he also doesn't think a chip is the answer. He says the ECM could be, so could TB bushings (he said another CF member - I think Steve Oldis?? - rebuilds TB's using ball bearings instead of bushings). I'm going to try jiggling the throttle to see if I have any play. The TB was re-built last year, but maybe the bushings weren't very well set and have come loose?

I tried finding an auto store that sells a prom removal tool, but no luck.

Does anyone know where I can get one of these without buying a new chip?

I agree about a slightly higher idle - I prefer 800 to 600. A steady idle at 800 rpm would be just great.

davemack

Thought so, but didn't want to fry my ECM. I'm on it tonight.

I'll also give it a final look for vacuum leaks. Seems so odd that a vac leak would be such a random thing vs. continuous. But, what do I know?

kopbet89c4

I have a feeling that your TB blades are not closing properly or completely and sometimes closing ok. If they are just barely propped for some odd reason, your idle will be high as if you adjusted the stop screw on the TB. When they are fully closed, the idle will be correct.

I'd take off the TB for examination and verify that the TB blades are seating correctly against the walls and not intermittently propped against a rough area or edge.

ps: This would also be the perfect time to do a TB coolant bypass.

davemack

Worth a try. I did check the fuel/air ratio using the on-board diagnostic. For the most part, it looked like equal parts check engine light and nothing. I guess that means that fuel mixture is roughly correct?

No success in locating a vac leak. I sprayed everything down pretty good with carb cleaner and no change in idle speed.

Same with throttle linkage - tried shaking it and no movement.

I did an anti-freeze flush and fill and installed a new coolant sensor on Saturday - I did the TB by-pass at that time. I'm still unsure if I like the by-pass - the hose that conects under the TB seems to kind of crimp a bit. Too much stuff located right in that general area, but it does flow.

I'll pull the TB again tomorrow and see what I can find. I did pull it about a month or so ago, sprayed it with intake cleaner, wiped it down, sprayed the TB rod where it attaches to the plates w/WD40, sprayed the spring around the throttle linkage and installed a new IAC ( I removed the IAC and TPS before I cleaned the TB at let it dry in the sun for a couple hours before reassembling). No difference. I gave 'em another light shot of WD40 this past Saturday as well.The throttle plates were still very clean when I cleaned the TB- only a trace of carbon film. I've also tried many times opening and closing the throttle to see if I can get it to hang up. It seems to seat fine.

Question: how much gap should I see at the base of the throttle plate? Does it change when the key is in run position vs. no power? My gap with key off looks very small, very nearly closed. My min air is set at 450 rpm (give or take with the idle thing going on), TPS at .54v. If it should be a noticeable gap with the key off, I'm not seeing it. I've never thought to look at it with key in run position (but not running).

I had no success locating an auto parts dealer that sell a prom chip removal tool. I suppose I'll bring it to the shop tomorrow and see if they'll do the chip swap (with me watching over their shoulder to make sure they install the chip correctly!).

Will report back tommorrow PM.

As always, thanks KopBet89C4 and Rick for the excellent advice. It does seem like we're making progress - it idles more often than not as it should.

davemack

Guys - I'm trying to replace my ECM. Is there any trick to removing the "hush panel"? I could easily remove the black plastic piece in the back, but the carpert covered part and the breadbox seem like their glued on.. I can see some brackets that appear to hold the breadbox in place, but no idea how to remove, or worse, if I could remove them, how I'd reattach. I cannot see any screws holding the carpeted piece in, but it's not moving a bit.

Help!

goldeneye_vet

As in your post about removal of the ecm all you need to do is remove the plastice peice and look up. 2 10mm bolts holding a white peice of plastic with a silver box attached. Undo and gently pull down.

davemack

Thanks, Goldeneye_vet,

I did as you suggested and it worked great.

Now, for the real reason for the post..

I swapped my ECM. Didn't seem to change a thing. I was really hoping I'd fire it up and it'd run smooth as silk..

I think I need to bring it into the shop. I've rebuilt the TB, replaced the injectors, replaced the O2 sensor, replaced the TPS, replaced the IAC, replaced the coolant temp sensor, by-passed the EVAP, set min idle at 450, TPS at .54v, re-set IAC pintle at 1 1/8 inch extension, sprayed the throttle plate rod connections and linkage with WD40, removed and cleaned the TB, sprayed the MAF with MAF cleaner, replaced the ECM.

Still idles like sh*t. Maybe I need to advance the timing to get a higher rpm idle? It seems to feel stronger when it idles at 800 rpm than at 600 rpm. When idle drops below 650 rpm, the lights on the dash begin to dim as the engine goes into it's low rpm lope, like it's going to stall. Still smell raw fuel in the exhaust, but in field diagnostic mode, ALDL says mostly proper mixture (neither lean nor rich).

Then again, if I advance the timing and increase the rpm, I'll prolly blow the damn engine when it goes into psycho surge mode. Oye.

Fuel pressure with key in run position (but not running) is 34 psig, it's 31 psig at idle. Did notice an occasional dip in FP to around 28 psig, but thats still within normal range. No smell of fuel in vac hose or fitting to FPR.

No vac leaks could be found. I've sprayed liberally with carb cleaner, nothing. Checked EGR, holds vac and bleeds down as per spec.

What do you guys think about disconnecting the lead to the cold start valve? Will this make it too hard to start? It's cool up her in MN, but not freezing.

Very bizarre. I've never seen a car so confounding.

goldeneye_vet

NO, don't disconnect the cold start injector. That isn't going to solve anything and it will make it harder to start. In my previous post's I gave you the link to WINAldl. From that website is a link to a cheap homemade cable that can be made with a few parts from RadioShack. Get that thing made and get some datalogs to analyze what you are seeing. This is like the blind leading the blind as I'm having problems too but I've got other issues and I wish to high heaven I had a stock setup again. I so miss just getting in the car and driving it. Stick with it and don't take it to a shop just yet. You mentioned that you had checket the TPS but have you made sure that all of the washers are between the bolts, the tps and the TB? Without all of the washers (one just underneath the head of bolt on the side of the TPS and the other on the backside of the TPS before it meets up with the TB) your TB blades will stick because the TPS is too tight and not being allowed to return to normal as it is stuck. This is a complete shot in the dark but again it's worth checking. This could possibly cause the idle to stick but movement of the vehicle over a bump or road is just enough to loosen it.??????????? That one is a big MAYBE but just double check. You'll get there....time is only holding you back.

davemack

Goldeneye_vet,

You did indeed give me the info on the WinALDL and instruction on making the cable. Thanks again for that.

I was hoping to buy a cable for $25 (another helpful CF member knows of someone who sells these). I completely agree, though, I gotta datalog the darn thing.

And, BTW, Radioshack also carries PROM chip removal tools for $11. I called all the autoparts stores and no one carried the tool. Mentioned it to a guy at work who suggested Radioshack. makes too much sense..

I will check the TPS. I don't recall any washers between the TB and TPS, only the special washers on the outside as well as a couple of lock washers to hold the screws in place. But, I'll check. That may well explain the high rpm issue.

Thanks again for the encouragement and advice.

davemack

Did a quick check - no washer between TB and TPS, Installed small locking washerson both sides of the TPS (the locking washers have the smallest OD - I didn't want the top oneterfering with the TPS lever).

Will report back on that tmorrow.

kopbet89c4

Yes, more advanced timing should result in a higher, more stable idle. The factory timing on the L98 is 6 degrees BTDC. I've had my timing as low as 2 degrees trying to diagnose my pinging problem, but it seems like its struggling to idle. I have mine set at 10 degrees BTDC and it feels a lot peppier compared to the factory 6 degrees GM recommends in the manual. Just run 89 octane or higher.

So your dash is dimming with your low 600 rpm idle??? Sounds like your alternator is kinda weak. I think factory amperage rating on the stock alternators is 105 amps. I have a 140 amp on on mine because I got mine for free on my B-day about 4 months ago. Thanks to a friend of mine at NAPA...

RRT vette

Dave, this threads gotten so long I have missed a few things, perhaps start another thread listing the problem still and things you have done. Another suggestion I would do, if it hasn't been suggested already, is check/clean all grounds around the engine bay and at the alternator and batery. Loose grounds can cause wierd things.

davemack

kopbet89c4, RRTVette,
Thanks for weighing in. I did check the battery without car running, around 12v, then when idling, around 14.7v or something. Anyway, it seemed to be charging as it should and I'm sure it was within spec. But, maybe that's not an effective way of assessing the alternator? I read in the FSM that if I touch the tab and housing with a screw driver, I can measure output from the alternator, but it also says if I do this too long I can ruin the alternator.. I chickened out.

I think I will advance the timing. I have nothing to lose by trying, and I agree that it runs much stronger with 800-850 rpm idle.

I'll give the grounds, such as I can locate them, a good visual and clean/tighten.