Jan Olsson Posted January 24, 2008 Report Share Posted January 24, 2008 In that test you (with engine shut off) fire each injector individually and can measure the pressure difference in the fuel system before and after to find out if an injector is clogged or leaking. Don't have to do anything else than to connect a fuel pressure meter to the schraeder valve on the fuel line. Sounds good, but there are 8 injectors, 8 injector to fuel rail o-rings, an FPR, and an inlet o-ring that are possible leak points. The question is which one...... With this test you could se that for instance no. 5 injector fuel pressure difference was different from the others, the pressure difference would become 0 or near 0 if it was stuck open. This test does not have anything to do with the FPR, you just measure the pressure difference not the absolute pressure in the system which would indicate a faulty FPR if it was off the limits. SO you would know that the no. 5 injector was bad. The outer (green) seating ring has nothing to do with this either. It just seals the combustion chamber up. The o-ring would cause a visible leak outside the injector right? Just my 2 cents Link to comment Share on other sites More sharing options...
jackc Posted January 24, 2008 Report Share Posted January 24, 2008 OK. I understand now. I wish I'd have known about that test at the time. I still toy with the idea of replacing my injectors again, but have been gun-shy from my last try at it. I did have my original injectors bench-cleaned at the local fuel-injector service shop. They reported that they got lots of crud out of them and that they had significant flow variances, even after the cleaning. If I could just find a really good price on a set of brand new AC Delco injectors.......... Link to comment Share on other sites More sharing options...
Ion Posted January 24, 2008 Author Report Share Posted January 24, 2008 If I could just find a really good price on a set of brand new AC Delco injectors.......... A local injector guy quoted me a price of $500.00 to test my existing, then, if some are indeed bad, replace them all with Multeck, which, according to him and parts dealerships, are OEM. (If they are deamed to be ok, there would only be a small service charge for the test). I'll let you know how this pans out. If all goes well, this would be quite a substantial savings from the prices quoted me by parts dealers, ie. Carquest, et.al. ($160.00 and up per!) Link to comment Share on other sites More sharing options...
jackc Posted January 24, 2008 Report Share Posted January 24, 2008 Rockauto.com is currently getting $100.99 for the new AC Delcos. They have the re-mans (originals that have been tested, cleaned and flow-matched by GB Remanufacturing) for 30.79 + $10 core - but it was one of the GB's I got that was bad..... The option your guy is offering doesn't sound too bad if he's on the up and up - but if I was in your situation, I might be tempted to try the GB's again. Rockauto did give me a full refund when I ran into problems - no hassle at all. Link to comment Share on other sites More sharing options...
KHE Posted January 24, 2008 Report Share Posted January 24, 2008 $500 for that job is awfully pricy... did you check this shop? http://www.cruzinperformance.com/fuelinj.html I used them once on my '86 Park Avenue and they were very reasonable - about $70 to flow test and repair 6 injectors. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
BodybyFisher Posted January 24, 2008 Report Share Posted January 24, 2008 I replaced the following: 1. Fuel Pump 2. Fuel Filter 3. MAP Sensor 4. TPS 5. FPR First start in the morning, car starts right up, or...after car has sit for extended period of time. On the other hand, after running car to store, etc, (where it has not sit for extended period of time), starter will crank excessively before engine kicks in. CONCLUSION: fuel is leaking into valves or cylinder after shutting off. If car sits for extended period of time, backed up fuel evaporates, thus alleviating excessive starter cranking. Not allowing backed up fuel to evaporate causes extended starter cranking & black smoke. I believe this issue lies with the injectors. After all, the Northstar has over 100K miles on it. My guess is they need to be serviced, but noone in my town does this. Can someone refer a place for me to ship them for service? Sounds like the EGR valve. Exhaust Gas Recycle Valve is NOT the source of the problem. For one thing it was replaced a couple years ago, furthermore, a faulty EGR would not cause fuel to leak into the cylinders after shutdown, causing flooding, extended cranking, black smoke, etc, upon hot starts. In addition, it would set a code Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Ion Posted January 24, 2008 Author Report Share Posted January 24, 2008 UPDATE 1/24/08: Just had the injectors tested...electrically and mechanically, they are in perfect working order. WTF?!?! Now what? I ordered a seal & o-ring kit for them from a local GM dealer and will get them in next week. I noticed one o-ring was bad and a couple seals had some minor chunks missing from them, but would that cause my documented issues? After all the fuel-delivery parts I've replaced and all the time spent doing it, without solving the problem, I am about ready to throw in the friggin' towel and bring the car into a mechanic. Any last suggestions? Link to comment Share on other sites More sharing options...
Jan Olsson Posted January 24, 2008 Report Share Posted January 24, 2008 UPDATE 1/24/08: Just had the injectors tested...electrically and mechanically, they are in perfect working order. WTF?!?! Now what? I ordered a seal & o-ring kit for them from a local GM dealer and will get them in next week. I noticed one o-ring was bad and a couple seals had some minor chunks missing from them, but would that cause my documented issues? After all the fuel-delivery parts I've replaced and all the time spent doing it, without solving the problem, I am about ready to throw in the friggin' towel and bring the car into a mechanic. Any last suggestions? You don't have any codes? My thinking is perhaps your idle speed control motor i acting up. Check your fuel pressure. Perhaps its off limits? Link to comment Share on other sites More sharing options...
jackc Posted January 24, 2008 Report Share Posted January 24, 2008 I replaced the following: 1. Fuel Pump 2. Fuel Filter 3. MAP Sensor 4. TPS 5. FPR First start in the morning, car starts right up, or...after car has sit for extended period of time. On the other hand, after running car to store, etc, (where it has not sit for extended period of time), starter will crank excessively before engine kicks in. CONCLUSION: fuel is leaking into valves or cylinder after shutting off. If car sits for extended period of time, backed up fuel evaporates, thus alleviating excessive starter cranking. Not allowing backed up fuel to evaporate causes extended starter cranking & black smoke. I believe this issue lies with the injectors. After all, the Northstar has over 100K miles on it. My guess is they need to be serviced, but noone in my town does this. Can someone refer a place for me to ship them for service? Ok - Back to the begining. You started here. Did your car have the hot hard start problem before you replaced these things? Link to comment Share on other sites More sharing options...
Ion Posted January 24, 2008 Author Report Share Posted January 24, 2008 Ok - Back to the begining. You started here. Did your car have the hot hard start problem before you replaced these things? I'm 100% sure the hot start issue was not present after I replaced fuel pump and filter. The old one def. went bad. I'm fairly sure that after TPS and MAP, the hot start issue did not exist. I'm also pretty sure the hot start issue began before I replaced the FPR, not after. The bucking and rough running & black smoke have been occuring randomly since last summer...before I replaced the MAP, TPS and FPR. Interesting note: I just spoke with a Caddie service guy in Vegas who suggested I look at the main fuel rail inlet, where it snaps onto the fuel line and see if the cover was still on it. It was not. Likely during the several removals of the cover it had fallen down onto (around) the main fuel line nipple. I retrieved it and snapped it back onto the rail inlet connector (which has an o-ring inside it). The service guy said if that had hapened, it's possible fuel is flooding all inside from there, causing my problems. Unfortunately, I won't be able to determine if that was the source of my problems until my injector seal kit arrives from GM, sometime early next week. The service guy also told me to be sure the new FPR is making a good seal with the fuel rail, which it is. Link to comment Share on other sites More sharing options...
BodybyFisher Posted January 25, 2008 Report Share Posted January 25, 2008 Why don't you summarize what you have done so far. Don't get frustrated, start over as someone else said. You HAVE accomplished one thing, you can ELIMINATE the injectors... 1) did you check the fuel pressure, when the condition occurs? 1a) in 1994, they might have two methods of engaging the fuel pump, a fuel pump relay, and if it goes bad, the oil pressure switch, check the fuel pump relay. I think this came up before and I was smacked down because they eliminated the oil pump switch that engages the fuel pump in the event the relay bombs out, but think about this for a 1994 engine, 2) did you kink the fuel lines doing the job? brainstorming here.... 3) replaced FPR with OEM or aftermarket? 4) when the car finally starts warm do you hear valve train noise? (oil thinned out, lifters collapsing) 4a) any codes at all? history or current 5) swap in a known good ignition module bad ignition modules will mess up hot, has it been out?, if it has, did you put the heat sink paste on it when you put it back 6) what have you done with the PCM? Did you swap in a good one? Have you put in any aftermarket K&N or cold air intakes that stopped pulling air over the PCM? 7) Reset all connections at the PCM and coils Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Ranger Posted January 25, 2008 Report Share Posted January 25, 2008 Have you cleaned the EGR & mouse holes? Are you sure that the manifold cover gaskets are in good condition? Is the ISC motor working properly, that is cracking the throttle plate to allow intake air at start up? Sorry if these were already covered, but I did not reread all 30 some posts. Link to comment Share on other sites More sharing options...
Ion Posted January 25, 2008 Author Report Share Posted January 25, 2008 I forgot to mention I got a new intermittent MAP signal error (P071) again, despite replacing the MAP sensor a couple months ago. I'm sure the sensor is fine, but there might be an issue in the manifold? Maybe I didn't torque the torque screws exact enough (between 8-11 newtons) on the cover? Maybe one of the rubber spacers beneath them is bad? Or...maybe I put the two long torque head screws in the wrong position? Last time they were put in on the driver's side, under the sparkplug wire enclusure. Interestingly enough, the last time I was getting P071 errors, was before I decided to replace the MAP sensor. While getting these errors, the car was bucking, cutting out and generally driving like sheet, but was not experiencing hot starting issues. I've had enough for the time being. Hopefully this will strike a chord with someone and they will have a "duh" fix for this. Link to comment Share on other sites More sharing options...
Ion Posted January 25, 2008 Author Report Share Posted January 25, 2008 Have you cleaned the EGR & mouse holes? Are you sure that the manifold cover gaskets are in good condition? Is the ISC motor working properly, that is cracking the throttle plate to allow intake air at start up? Sorry if these were already covered, but I did not reread all 30 some posts. I took off the EGR several weeks ago and holes were in good shape, plus it was replaced a few years back. What is an ISC motor? And once again, I'm still confused how an EGR could have anything to do with flooding? Please enlighten me, as I am not a mechanic and am open to learning anything new about this northstar I can. Link to comment Share on other sites More sharing options...
Ion Posted January 25, 2008 Author Report Share Posted January 25, 2008 Why don't you summarize what you have done so far. Don't get frustrated, start over as someone else said. You HAVE accomplished one thing, you can ELIMINATE the injectors... 6) what have you done with the PCM? Did you swap in a good one? Have you put in any aftermarket K&N or cold air intakes that stopped pulling air over the PCM? The PCM, which was replaced in 2002, is located behind the glovebox, so there is no air passing over it whatsoever. 7) Reset all connections at the PCM and coils I did pull it out a couple months ago and reset all connections. Link to comment Share on other sites More sharing options...
jackc Posted January 25, 2008 Report Share Posted January 25, 2008 Does your ignition module have a big ground wire coming off of it (from one of the mounting bolts) and going over to the fender? Mine does - and it looks like something that someone has added. Some of this sounds like a flakey module - bad ground maybe? Link to comment Share on other sites More sharing options...
Ranger Posted January 25, 2008 Report Share Posted January 25, 2008 EGR was just a shot in the dark. If stuck open it probably won't start or will die shortly there after. ISC (Idle Speed Control) motor is the small motor with a plunger on it that controls the throttle lever. If it does not open the throttle, the engine is choked and will not start. You could rule that out by lightly pressing on the gas pedal to give it some air. Neither will cause a flooding problem. Link to comment Share on other sites More sharing options...
jackc Posted January 25, 2008 Report Share Posted January 25, 2008 The bucking and rough running & black smoke have been occuring randomly since last summer... If we put aside the hot hard-start issue and just look at this, where would it take us? Is the black smoke just a by-product of an ignition problem that's causing the random bucking and rough running? Link to comment Share on other sites More sharing options...
Ion Posted January 25, 2008 Author Report Share Posted January 25, 2008 The bucking and rough running & black smoke have been occuring randomly since last summer... If we put aside the hot hard-start issue and just look at this, where would it take us? Is the black smoke just a by-product of an ignition problem that's causing the random bucking and rough running? Would anything related to ignition cause flooding, which in turn, causes the hot start issue? I suppose there could feasably be more than one issue occuring simultaneously, one relating to flooding, the other relating to the rough running issue? Link to comment Share on other sites More sharing options...
Ranger Posted January 25, 2008 Report Share Posted January 25, 2008 Black smoke is generally an indication of running rich. Ignition should have nothing to do with flooding. Two separate issues is a possibility. Link to comment Share on other sites More sharing options...
Ion Posted February 2, 2008 Author Report Share Posted February 2, 2008 UPDATE: All injectors tested to be in perfect working order, both physically and elec. I replaced seals, where a couple had visible deterioration, re-attached cover to the fuel rail inlet (had fallen off and was sitting around nipple) and replaced missing o-ring underneath FPR. Once cover was torqued back on, I did a carb-cleaner test to see if it was leaking and it wasn't. Hot start issue is now gone! BUT...now I'm back to the old 071 & 095 errors, where engine just randomly DIES!!!! I'm back to thinking my once replaced PCM ('01) might be the source. I referred back to: http://caddyinfo.ipbhost.com/index.php?sho...p;hl=map+sensor and was hoping someone had the NEW part number that replaced the bad numbers listed in that post? I'm going to pull out my PCM and see what part number is on it in the meantime. Link to comment Share on other sites More sharing options...
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