Car:
88 Vette, new 383, AFR 190s, LPE 219 cam, Hookers, 58mm TB, Superram plenum, 30lb used Ford Injectors, Ported Edelbrock hi-flow intake man, comp cams roller lifters and 1.6 roller rockers, Stock 165 comp, ABTP code with mods to MAF vs diags-Injector Const-fan temps. Has 2 O2 sensors. 1 in pipe #7 that runs a gauge in the ****pit, and a heated one in the Y pipe just past where it joins and 6-8 inches before the main and only cat that .

History:
Motor has been in for about 25 miles and I have been modifying the stock ABTP code. Modifications include disableing the MAF diag so that I don't get code 33 anymore, lowering the fan temps, and playing with the injector constant. I worked my way up from stock to 29#, with 29# causing BLMs from 118 to 124 depending on the cell. 31# was causing BLMs to go off the scale on the high end. AFR guage in ****pit shows slightly rich. Saturday Afternoon I fixed a problem with the throttle cable(was only allowing it to open 1/3 to 1/2 way), and oh my did I get a smile on my face for the few runs I logged. Below 1000 rpms, it surges and has a very rough idle. IAC counts are 0 so I am assuming I have a vacuum leak?

Problem:
Bumped the injector constant to 30# to see if it would globally lean the curve a little closer to 128. Reset the ECM. Start it up allow it to go to closed loop. BLMs peg at 108. If I give it enough gas to go to a new BLM cell, it pegs to 108. Weird thing is that when I go to a new BLM Cell, the guage shows it is close to stoich then progressively leaner as the ECM corrects to 108.

Additional info:
No codes. Tryed putting back the 29# chip, and it now does the same thing.
Swapped the cables on the O2 sensors so the #7 tube was running the ECM and the heated one in the Y was running the guage and it still did the same thing which really confuses me.
Last weekend, I put Valvoline Injector cleaner in when I filled up since I bought the injectors used.
Also after a little spirited teston (only to 5000 rpm) I developed a small oil leak. When running oil drips in the pasenger front area. From underneath, it looks like it is coming from the fuel pump bypass or higher, but I cant see above do the the AC.
Hooked up a Fuel Pressure Test Guage and upon initial key on, pressure goes to 42psi, but with 30 seconds has dropped to 30 and after a couple minutes has dropped to 20 and continues to more slowly drop.
I haven't had time to check the plugs yet.

Questions:
What could cause the sudden change?
Injector cleaner did a great job?
Injector stuck open?
Why would swapping the O2 sensors give me the same result?
Maybe the wire between the connection and the ECM is bad/flakey causing it to be a little high?
What do I check next?
If I am chasing too many probs, what should I do first?

[This message has been edited by Warlock (edited August 27, 2001).]

 

Well I am not sure if this will help..

I would install the FP gauge and tape it to the windshield and drive around a bit and as you go WOT. the fuel pressure should go to your MAX setting and hold. if it starts to fall off.. Replace your fuel pump.

otherwise. on my 89 with 24# SVO injectors. I set the code for 26# and at poart throttle I think I am very close to 128 BLM

------------------
-=Jeff=-
89 Corvette Coupe White with Black Grand Sport Stripe
-=ICON Motorsports=-
Check out my mods on My '89 Vette

 

Just an FYI, SVO injectors are rated at 24 & 30pph at 37.5psi. Using them at GM's 43psi causes the system to run rich, so a 30pph acts like a 35 or 36pph GM.

Just a heads up.



------------------
Kelly 'GhoSSt' Rosato
1996 Impala SS, 383 LT4 (14.65 up here, 13.24 lower)
1984 Firebird, +.060 350 (Vortech Heads, HOT Cam, and schtuff)
1993 Caprice, 5.7 TBI (stock . . . FOR NOW)

"And if you wrong us, shall we not revenge? Revenge. The villany you
teach me, I will execute, and it shall go hard but I will better the
instruction."

Shylock in Act III, Scene I of 'Merchant of Venice' by William Shakespeare

 

Take it one at a time!!! First off- with a new engine-get a few miles on it before you drive yourself crazy with tuning-and go easy on it! I found; and lots of other folk too, that the sealers you use(silicone etc.) in a new engine will waste the O2 sensors until they "burn off". I just used my old one until I had a few hundred miles on it, then put in a new one-and the old one looked coated! I take it you have a scan tool or software? How's the O2 sensor look? Fast transitions? Also ditto the above advise on checking fuel press. plus check that the injectors are not leaking-that would do it also. Hope this helps.



------------------
86 406

 

Well the oil leak could be from one of the bolts on the front of the block that go through some kind of bracket. I am not sure about how a vettes brackets are, but on mine it had a bracket that the AIR pump went on. The deal with the top one of those two bolts on the lower part of the front of the passenger side of the engine is that the hole is drilled so deep sometimes that it enters the area where the fuel pump push rod goes. So oil will seap past the bolt threads. I had an engine do this and a little liquid teflon on the bolt and that took care of it.

Good luck....

------------------
1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, BBK 52mm TB, Edelbrock TES, gutted Cat, Flowmaster, CAI w/K+N cone, AFPR, TB bypass, !AIR, !A/C, !EVAP, ARAP, 2300 stall, Alum. Driveshaft, Hotchkis STB, '99 Camaro seats.

Coming Soon!!: Fourth gen 3.42:1 rear, Spohn LCAs and Panhard.

 

Thanks for the ideas and keep them coming. I have been preparing for a week-long backpacking trip that I leave for tomorrow. I will work on this as soon as I get back.

 

I tried 30lbs injectors on my L383...for 3-months I kept having problems like yours. I finally gave in to 24lbs injectors and life is great..that you GM Diacom Plus!

V/R,
Frank

 

When you get a chance try setting the injector constant to 33 or 34lb hr. Also make sure that IF you are using WinBin that you are running the latest version of the software and the most recent $6E ECU file that has been published on Zaphod's site.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Warlock
I think Matt hit your oil leak on the button.
I and a few others had this same leak. Yes in front of the block where a early stly fuel pump would be there are two bolts holes that are threaded all the way thru where the fuel pump rod should be. This was for early setups. you thread in a long bolts to hold the rod up. If you have a new preped block this bolt may have been reomoved when the blockwas cleaned.
I just installed some bolts with RTV on them . All good


------------------
85 vette,383,miniram,ZF6,4.10's..best ET 11.56@119.00 60' 1.59
w/100HP nirous 11.05@127
http://geocities.com/bowtie8
http://bowtye8.tzo.com