Guest Simpson36 Posted January 9, 2006 Share Posted January 9, 2006 OK, I am starting my journey into the mysterious world of cross fire tuning and I really need the advice and perhaps help of some of the experienced wizards that prowl this forum.This weekend I got around to doing a leak down test on our CE. All cylinders check out excellent except for a (slightly?) leaky exhaust valve on cylinder #8. Plugs all looked good but I replaced them anyway with the correct R45'sI also made a fuel pressure test rig as shown in the factory manual and tested the fuel pressure. It is a steady 12 lbs and drops to 11 when the the throttle is blipped hard.I replaced the 02 sensor with a new OE type single wire part.Here's the interesting part: I noticed that the part numbers and manuf date of both injectors is identical . . . and the year ends in 8, so obviously both injectors were replaced sometime after 1988 or 1998, and I would assume by someone who didn't know that the injectors are different front and rear.Both injectors carry part number GM5233770*RPD and date N028. My research shows these to be rear injectors of the original type (the current replacement GM part numbers have changed).When we first got the car last summer, I noticed that the rear injector doe not spray the same as the front, but I was told by the Vette shop that injectors either work or they don't and that there is no in-between, so I chalked it up to the difference in the front and rear injectors (which I already knew were different for front and rear).The front injector (which is actually a rear injector installed in the wrong place) sprays a wide even cone of fuel which seems to hit the bore wall. The rear injector sprays a much narrower cone which is a bit dribbly on one side and it seems to spray onto to throttle plate.So actually, I think I have one good rear injector (now in the front) and I would only need a correct front injector (GM5233775*RPD), but the GM part numbers have changed and I am worried that I should replace both as a set in case there are some differences in the replacement injectors.Can anyone shed some light on this?Does anyone have a spare working GM5233775*RPD (front) that I can try out to see if this is the cause of the rough idle?We want to keep our CE as original as possible and I have done a lot of looking and cannot verify if some other numbers on the TBI's are correct. Here are the numbers. Anyone know if theses are the correct original parts and if they are in the correct location?TBI body Rear 17082052Front 17082053TPS AC C46 D7063Regulators - number stamped into top plate that covers the regulators:Rear 70607Front 70608GMpartsdirect shows different part numbers for these items, but like the injectors, that may just be due to combining a bunch of original numbers under one replacement number, but so far I haven't been able to find a source for this info. Link to comment Share on other sites More sharing options...
Desertdawg Posted January 10, 2006 Share Posted January 10, 2006 When you looked at the plugs, about 4 of them should have looked like they were running a little rich (black), it's just the way the crossfire manifold is, some cylinders get more fuel than others...Your fuel pressure test is a good example of why all the CFI owners preach about swapping out your original stock fuel pump for an 85 or newer model pump, (exact replacement fit). The CFI was designed to run at a fuel pressure of 13 to 14 PSI, yours is just barely enough to run at WOT. with the 85 or newer pump you will be at a solid 13 to 14 PSI even at WOT... I did it to mine, and the swap was simple, and YES I did feel an improvement in performance...Don't replace it with another stock 82/84 pump, you will have the same low readings. And no one will ever see it inside you gas tank...Here's the correct part numbers for the L83 injectors (350 Cross-Fire) GM5233770*RPD (rear) GM5233775*RPD (front) I would contact Fred at jtauto@comcast.net about a new set with the correct part numbers for your 82.You can also try www.fiveomotorsport.com. You can place orders via the net or over the phone with "Bruce". I talked to him a year or so ago and he sounds very knowledgeable about injectors. The website shows a huge selection to fit different makes. The price for our injector replacements, each different from the other, are $60 each, plus a $70 core charge (for BOTH) and s/h, He sends the units to you, and after making sure all is right w/them, you send your old set to him and you are refunded the $70. These are made by Bosch, so they should be of good quality.When you see a dripping injector, it's telling you that it is time to rebuild or replace them, you probably have something plugging the pintle in your rear injectorI checked the old set of TB's I have and the part numbers are:17082052=rear17082053=frontAnd remember, it you remove the TB's from the intake, you will have to re-balance them or it will run rough!!! Link to comment Share on other sites More sharing options...
Guest Simpson36 Posted January 10, 2006 Share Posted January 10, 2006 Thanks Dawg!Based on info from theses forums, I replaced the FP with an '85 Delco a few months ago. The car pulls strong at WOT all the way up to it's 4,500 RPM shift point without a hint of stumble. The car cruises great with no surging. It even handles and tracks great now that the A-frame is no longer falling out!Really, the only problem I have is the rough idle. I did a compression test (excelent result) when we first got the car last summer and put in all new ignition wires, plugs, cap, rotor, etc. which helped a lot.I paid a lot of money to a self proclaimed 'cross fire expert' who accomplished nothing but trying to cover the problem with stupidly advanced timing and an improperly set TPS. He supposedly balanced the TBI's also, but a quick check with a vacuum gage showed that they were not even close.So I am determined to learn about the system and tune it myself. I bought a laptop and got Win ALDL working. I was just waiting to make sure the engine was mechanically OK before I started into the induction side. Last weekend I did a cylinder leak down test (VERY cool tool) and the engine is good to go, so I'm into the injection system now. WinALDL showed the 02 sensor jumping all over the map at idle, which could be caused by the induction system, but I replaced the 02 sensor just in case. The plugs were all textbook when I first changed them after a thousand mile road trip (driving the car home) and again last weekend after a few hundred miles of around town driving. No oil, no water, no rust, no black soot. A fellow in Alabama has the correct front injector and is going to send it to me. I already have what appears to be a working rear injector, so hopefully I will get a good result from installing the correct injectors.Question: is 'injector cleaning' legitimate? The 'expert' told me that injectors either work or they don't, so there is no purpose to cleaning them. But I'm looking at two identical injectors on our CE which both 'work' but the spray pattern is very different. I suppose it could be a difference in pressure, but I think it is unlikely that the injectors are intended to work this way.Thanks for the links for injectors. I'll check them out. GMpartsdirect wants $110 each plus $25 shipping for each injector. I don't even want to THINK about what a dealer would charge . . :-)We are looking forward to meeting the 'Vette people. Are there regular meetings or hangouts? Link to comment Share on other sites More sharing options...
BSeery Posted January 11, 2006 Share Posted January 11, 2006 O2 sensors will jump all over. The narrow band basically end up working like an on/off switch, jumping between rich and lean. The only time mine is steady is at WOT end then it stays at just a touch rich. Other than that, it goes back and forth all the time. The range is just not very wide . Link to comment Share on other sites More sharing options...
Desertdawg Posted January 11, 2006 Share Posted January 11, 2006 I have to agree, injectors either work or they don't, and when they don't you get no fuel at all...What your rear one is doing is leaking, it sounds like it works just fine for fuel delivery, but it's probably clogged or tarnished. maybe both...The way you described the front injector's fan type spray pattern is how they both should look. Why don't you contact Jim (Elkabong) and get with him for tuning, he is the master around here, and he can show you how to ready what your seeing on your laptop, as well as how to balance your TB's. When we did mine, it smoothed out the idle some, and that sounds like part of your problem... Link to comment Share on other sites More sharing options...
Guest Simpson36 Posted January 11, 2006 Share Posted January 11, 2006 Bserry:Thanks fir the tip. I did some reading today on the Neihoff site and they describe the 'waveform' of an O2 sensor going up and down as you described. The O2 sensor I took out looked new, so I probably didn't need to replace it. Methinks that the 550 prom is just so slow kicking out readings, it gives no hint thet the sensor is oscillating in any type of regular pattern. It apperas completely random.Dawg:There is a correct front injector in the mail to me. When I get that, I'll stick it in the front and then put the good rear injector in the rear. Once that's done and if the spray patterns look right. then I'll get some numbers from WinALDL and pow wow with ElKabong or anyone else who will put up with my endless questions . . . . :-).I think I am making progress though! Thanks for the responses! Link to comment Share on other sites More sharing options...
Guest Simpson36 Posted January 17, 2006 Share Posted January 17, 2006 This story ends well!!A fellow from Alabama (Eds82 from the crossfire Vault) kindly sent me the correct injector for the front TB on our CE. Putting a good rear injector in the back TB and Ed's correct front injector in the front TB and then balancing them made a HUGE difference!Everything is set factory stock; timing, fuel pressure, TPS, 195 stat, etc., and the car now has an appropriate fast idle on a cold start and idles down to a smooth and steady 600RPM idle in gear. IAC responds instantly to A/C and maintain 600RPM no sweat.Thanks to all who helped out with this aggravating problem! Link to comment Share on other sites More sharing options...
Desertdawg Posted January 18, 2006 Share Posted January 18, 2006 Really glad to hear you got it running good, now you can see what the rest of us like about the CFI setup... :D I think your going to need to road test it soon, be sure to check out the GIla Bend BBQ thread in the Events section Link to comment Share on other sites More sharing options...
azslim Posted February 8, 2006 Share Posted February 8, 2006 Dawg,How can I get a hold of Jim Elkbong? I may need his expertice some day. Link to comment Share on other sites More sharing options...
Desertdawg Posted February 8, 2006 Share Posted February 8, 2006 PM sent!Be sure to let him know where you got it from so he doesn't think your a serial killer or something... :D Link to comment Share on other sites More sharing options...
Guest Simpson36 Posted February 9, 2006 Share Posted February 9, 2006 Dawg:The Vette gets 'road tested' daily. It is my wife's commuter car . . . garage to covered parking, of course.And add us to your guest list for the BBQ! Nickolette and Steve Link to comment Share on other sites More sharing options...
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