Help!!
- Thread starter Steve87GN
- Start date
standupjskiguy
Member
- Joined
- Mar 18, 2009
Going back to the original problem. I suggest one or more fuel injectors is squirting. When cold the computer puts a
predetermined pulse for a cold engine. But when it warms, the oxygen sensor tells the computer that the engine is lean
because one or more injectors is not putting out enough fuel. I had this condition on a 92 Buick with a 3.3 liter engine.
In my case, one injector measured 4 ohms the rest about 12 ohms. All plugs were black.
Sitting so long, maybe electrical connector corroded or injector is gummed up shut. You might be able to carefully examine
the plugs and may find one is lighter than the others. Also if you can compare cold engine header pipe temperatures
you may find the weak cylinder.
predetermined pulse for a cold engine. But when it warms, the oxygen sensor tells the computer that the engine is lean
because one or more injectors is not putting out enough fuel. I had this condition on a 92 Buick with a 3.3 liter engine.
In my case, one injector measured 4 ohms the rest about 12 ohms. All plugs were black.
Sitting so long, maybe electrical connector corroded or injector is gummed up shut. You might be able to carefully examine
the plugs and may find one is lighter than the others. Also if you can compare cold engine header pipe temperatures
you may find the weak cylinder.
Steve87GN
Oh come on...its just a 6
- Joined
- Dec 3, 2005
Ok, time for a quick update. Got my set of RemFlex gaskets last week and my ScanMasterG today. So, this weekend's project is shaping up to be the manifold and my A-pillar gauge pod. I have a couple questions as far as the gauge installation, but I'll save those for another thread.
FWIW, the car does seem to run a bit better with new plugs and a new O2 (obviously, I know). One thing I have noticed, though, is that she does idle higher than before. Used to idle around 1000 rpm before the long sleep. Now she's around 1250-1500. Still going to get the ScanMaster readings and fix the manifold, but could this be indicative of a bad MAF (bad air flow reading) or TPS (reading throttle position wrong)? Just a thought I had. Thanks!
FWIW, the car does seem to run a bit better with new plugs and a new O2 (obviously, I know). One thing I have noticed, though, is that she does idle higher than before. Used to idle around 1000 rpm before the long sleep. Now she's around 1250-1500. Still going to get the ScanMaster readings and fix the manifold, but could this be indicative of a bad MAF (bad air flow reading) or TPS (reading throttle position wrong)? Just a thought I had. Thanks!
Steve87GN
Oh come on...its just a 6
- Joined
- Dec 3, 2005
Ok, time for another update. Got the Scanmaster hooked up and the exhaust sealed. Car runs great, but not perfect. BLMs are showing around 105-108 when idling and when under low throttle (cursing in traffic). Hard throttle only showed 0.5 retard once, which I guess is good. Will post more when I get a chance. Any particular scenarios I should test and sensors to watch?
Also, didn't realize how bad the digital tach is off. Sheesh!!! lol
Also, didn't realize how bad the digital tach is off. Sheesh!!! lol
Steve87GN
Oh come on...its just a 6
- Joined
- Dec 3, 2005
Ok, here's what I got last night. All readings are and have been closed loop. At idle in park, INT stayed 128, BLMs were around 110-ish. In drive at a stop, INT bounced briefly from 125 to 132, settling at 128 after a couple seconds, BLMs were the same as park. Driving up and down the street, INT was around 125 and BLMs were around 108. Looks like the integrator is happy at least, right?
Could this just be the injectors messing with the BLMs? They're less than 10% higher than factory, but that's the only thing I can think of. MAF readings are around 7 idling, 30-45-ish driving, higher when playing with the throttle. That's about right, isn't it?
Could this just be the injectors messing with the BLMs? They're less than 10% higher than factory, but that's the only thing I can think of. MAF readings are around 7 idling, 30-45-ish driving, higher when playing with the throttle. That's about right, isn't it?
- Joined
- Feb 18, 2006
That's not extremly bad. There is still room for correction on the blm. Int's are not as important.
Could be a few different things causing it to be a little rich.
What chip are you running? Also what MAF? And what is the fuel pressure set at?
Rick
Could be a few different things causing it to be a little rich.
What chip are you running? Also what MAF? And what is the fuel pressure set at?
Rick
Steve87GN
Oh come on...its just a 6
- Joined
- Dec 3, 2005
Ok, had a few minutes to mess with the car. Here's what I'm seeing at idle in closed loop.
O2 mvs are either around 200-ish or 700-ish and bounce between those ranges
O2 CCs are in the 200s
BLMs are around the 106 range
LV8 is in the 50s
Any ideas what this could be pointing to? Thanks in advance!!
O2 mvs are either around 200-ish or 700-ish and bounce between those ranges
O2 CCs are in the 200s
BLMs are around the 106 range
LV8 is in the 50s
Any ideas what this could be pointing to? Thanks in advance!!
Street Lethal
Tech Anarchist
- Joined
- Oct 8, 2006
OBD1 ECM's should only have a 6% threshold for O2 correction, which places your 108 BLM and 10% larger injector sizing into perspective. Assuming you are running 30# injectors (less than 10% more than the stock 28#'s) I would either lower your fuel pressure to help get BLM's in the 120's again, or have a chip burned for the correct values...
gunzandgearz
gearzandgunz
- Joined
- Aug 24, 2015
I have to agree with chuck leaper and dank gn and say that I think that you are putting the cart before the horse on this one.If you are going to work on your own car,which is great as this is the only way we learn,start out by getting yourself some old school tools like a good compression gauge and a vacuum gauge as these will tell you a boatload. Run a compression test on all the cylinders to make sure that the engine is in good shape,if that turns out good, then install the vacuum gauge and see how that looks make sure the needle is Good and steady ,if it is,another good sign,the last tool for your box should be a thermal heat gun as you can point this directly at each individual header pipe, and if one or two of them is a lot cooler than the rest, those are your problem holes.These are all cheap and easy ways to diagnose the mechanicals of your engine.Now you can move onto the electronics of the system.I see this a lot on the modern day vehicles with guys chasing the computers or electrical components and the whole time the engine has a dead hole i.e. No compression.At least this way your not throwing your money at stuff that can't fix a mechanical problem.The main reason that I bring this up is if your exhaust leak at the header was run for some time it can actually burn a valve and you will have less compression on that hole and an infrared thermometer or compression gauge will reveal this,good luck.
Steve87GN
Oh come on...its just a 6
- Joined
- Dec 3, 2005
Well, its a good thing I've already got these tools. 
So, I don't have the time until maybe this weekend to actually do a compression test. However, I did have some time to hook up a vacuum gauge and check the temps on the primaries. Here's what I got:
Vacuum - fluctuated slightly between 15.5 and 16.5 with idle
Temps (measured near cylinder head unless noted):
1 - 410 2 - 700
3 - 493 4 - 687
5 - 550 6 - 600 (measured at base of primary)
There was no way I could get the temp gun near the collector of #6. Now, some notes. I attached the vacuum gauge where the MAP sensor is with a T fitting and some vacuum hose. The stock line fit over the T, but slightly loosely. When I pulled the gauge off with the motor running, the idle seemed to smooth. I would guess there was a very slight leak at the T. All other connections were solid. Also, the driver's side has the TA replacement manifold, so I would imagine that's causing the temp difference between the 2 banks. To me, it seems like #1 is a bit low compared to the rest (relatively speaking, of course). So, with all that said, any ideas? I'd prefer to not have to do a compression test (weekends are usually the only time I get some family time), but I will if needed. The car pulls hard and barks the Mickeys on the 1-2 shift with only about 1/2 throttle, which seems healthy to me. But, that doesn't mean everything is hunky dory either. As always, thanks in advance.
So, I don't have the time until maybe this weekend to actually do a compression test. However, I did have some time to hook up a vacuum gauge and check the temps on the primaries. Here's what I got:
Vacuum - fluctuated slightly between 15.5 and 16.5 with idle
Temps (measured near cylinder head unless noted):
1 - 410 2 - 700
3 - 493 4 - 687
5 - 550 6 - 600 (measured at base of primary)
There was no way I could get the temp gun near the collector of #6. Now, some notes. I attached the vacuum gauge where the MAP sensor is with a T fitting and some vacuum hose. The stock line fit over the T, but slightly loosely. When I pulled the gauge off with the motor running, the idle seemed to smooth. I would guess there was a very slight leak at the T. All other connections were solid. Also, the driver's side has the TA replacement manifold, so I would imagine that's causing the temp difference between the 2 banks. To me, it seems like #1 is a bit low compared to the rest (relatively speaking, of course). So, with all that said, any ideas? I'd prefer to not have to do a compression test (weekends are usually the only time I get some family time), but I will if needed. The car pulls hard and barks the Mickeys on the 1-2 shift with only about 1/2 throttle, which seems healthy to me. But, that doesn't mean everything is hunky dory either. As always, thanks in advance.
gunzandgearz
gearzandgunz
- Joined
- Aug 24, 2015
Luckily those cylinders are easy to get to you got almost 300 degrees difference in temperature that's a boatload check the compression ratio first in those holes I would do one three and two and four also make sure you have a good manifold vacuum reading that's a little low the manifold vacuum should be closer to 18 to 22 inches of vacuum these aren't small and big block Chevrolets with a lot of duration and overlap report back hopefully we can get your symptoms resolved there's no way the temperatures should be that far apart and the manifold shouldn't really have anything to do with it
Steve87GN
Oh come on...its just a 6
- Joined
- Dec 3, 2005
You don't think the fact that the passenger side is the factory cast iron and the driver's side is stainless steel will throw off the temp readings between the two banks? I would think the different materials would react differently to heat and absorb/dissipate it differently.
gunzandgearz
gearzandgunz
- Joined
- Aug 24, 2015
this is what I would do I would run compression test on all of the holes ,if that checks out good,I would use a spark tester that's adjustable so you can really load the coil the ones that have a thumbscrew on them and a clip for ground, if all checks good here I would start looking at checking injectors just offering advice hope you can find it I just know that I've been stung by this when I was younger technician more than once and I was chasing my tail when I should've checked the basics first if these tests turn out good that's great now we can move on knowing that that cannot be the issue also spark plugs will tell you a lot.
Steve87GN
Oh come on...its just a 6
- Joined
- Dec 3, 2005
Ok, time to revive this thread. Been a hectic year, but I've finally had some time to work on the car again. I've replaced the O2 sensor, plugs, wires, coil and ICM but still getting terrible BLMs. Based on what Street Lethal said, I'm inclined to believe its the injectors as well.
Now, I picked up an LT1 MAF and translator from Highway Stars (holiday package, great price, thanks Highway Stars!!) and just installed it. Set the Chip Type to All Others (1-3 ON, 4 OFF), MAF Base to 3 (Caprice/Impala MAF) and left MAF WOT at 0. BLMs jumped to 115-118 at idle and in the 120s when driving. Still getting terrible knock (almost 25 on the ScanMaster at WOT in higher RPMs), but it doesn't come on as much and the car definitely feels like it has more power.
I've got a PTE 5558 and THDP waiting to go on, but want to get a good handle on this first. After re-reading this thread, it seems like it would be best to either chip the car to match the injectors or, since I'm going to be upgrading the turbo, get bigger injectors and chip the car for those. Will chipping the car to match either current or new injectors alleviate this and potentially the knock issue? Is it common to have knock in a rich condition? Sorry for the noob questions, but I would rather ask more than assume anything. Thanks as always!!
Now, I picked up an LT1 MAF and translator from Highway Stars (holiday package, great price, thanks Highway Stars!!) and just installed it. Set the Chip Type to All Others (1-3 ON, 4 OFF), MAF Base to 3 (Caprice/Impala MAF) and left MAF WOT at 0. BLMs jumped to 115-118 at idle and in the 120s when driving. Still getting terrible knock (almost 25 on the ScanMaster at WOT in higher RPMs), but it doesn't come on as much and the car definitely feels like it has more power.
I've got a PTE 5558 and THDP waiting to go on, but want to get a good handle on this first. After re-reading this thread, it seems like it would be best to either chip the car to match the injectors or, since I'm going to be upgrading the turbo, get bigger injectors and chip the car for those. Will chipping the car to match either current or new injectors alleviate this and potentially the knock issue? Is it common to have knock in a rich condition? Sorry for the noob questions, but I would rather ask more than assume anything. Thanks as always!!
