New motor in...tach acting weird and engine cutting out?
06-09-2006, 09:16 AM
#1
New motor in...tach acting weird and engine cutting out? Okay, so I finally started driving with the new motor in last night. '98 Z28 6-speed. Added a freshened up lower-mileage shortblock and a 224/228 110*LSA cam and some ported heads with LTs.
Stock injectors right now until I get some 30# SVOs on Monday.
The idle is fairly decent but it likes to try and die with quick stabs of the gas...which makes sense. Overall drivability is decent for not having a tune whatsoever (getting dynoed Monday).
I have a couple problems. First...if I get on it fairly hard at all, I notice my tach start to bounce around like its not following engine speed like it should. I remember having this problem on my old '88 when I installed an MSD 6AL box and it didn't like it. I'm just about positive that I hooked up all of the grounds right. Two on the back of the head to the harness, one from the driver's side of the block to the framerail, and then the one by the starter to the thick negative cable that ends up going to the battery. This wouldn't be anything the tune would have an effect on would it?
Also from time to time if I'm getting on it a bit harder the engine will cut out and come back. It may be coming back just because I'm in gear though with the key forward (i.e. push start). When it does this the low oil light comes on for a few seconds, but I'm pretty sure my oil pressure is staying up. My oil is only a hair low on the dipstick...not enough to be causing any problems. Never had that issue with my old motor. I'm assuming this either has something to do with the tune or I have some bad coilpacks causing both issues maybe? It doesn't do this every time I get on it, its fairly random-seeming.
Do the coilpacks need to be grounded through the coilpack bracket or the actual valvecovers themselves? I don't have all of the bolts holding the coilpacks in right now because I have newer valvecovers but without brackets yet.
Stock injectors right now until I get some 30# SVOs on Monday.
The idle is fairly decent but it likes to try and die with quick stabs of the gas...which makes sense. Overall drivability is decent for not having a tune whatsoever (getting dynoed Monday).
I have a couple problems. First...if I get on it fairly hard at all, I notice my tach start to bounce around like its not following engine speed like it should. I remember having this problem on my old '88 when I installed an MSD 6AL box and it didn't like it. I'm just about positive that I hooked up all of the grounds right. Two on the back of the head to the harness, one from the driver's side of the block to the framerail, and then the one by the starter to the thick negative cable that ends up going to the battery. This wouldn't be anything the tune would have an effect on would it?
Also from time to time if I'm getting on it a bit harder the engine will cut out and come back. It may be coming back just because I'm in gear though with the key forward (i.e. push start). When it does this the low oil light comes on for a few seconds, but I'm pretty sure my oil pressure is staying up. My oil is only a hair low on the dipstick...not enough to be causing any problems. Never had that issue with my old motor. I'm assuming this either has something to do with the tune or I have some bad coilpacks causing both issues maybe? It doesn't do this every time I get on it, its fairly random-seeming.
Do the coilpacks need to be grounded through the coilpack bracket or the actual valvecovers themselves? I don't have all of the bolts holding the coilpacks in right now because I have newer valvecovers but without brackets yet.
06-09-2006, 01:49 PM
#3
Hmm I'll have to check. I don't remember missing any grounds (there aren't many on these cars for the actual motor/harness it seems), but I'll doublecheck. That's why I was asking if maybe the coils need to ground to the valvecovers/brackets. But people relocate them to the cowl area too, so that might not make sense.
06-09-2006, 02:05 PM
#4
Launching!
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i dont know if the 98 is different from the 2000 but i had 3 grounds in the harness that grounded to the motor i forgot one and my car wouldn't run at all. went back and checked sure enough one of the 3 wasn't hooked up
06-09-2006, 03:54 PM
#5
:doh: I knew I had those three hooked up, but I just checked them when I got home...and they were loose. I remember not tightening them now before I put the motor in. I was going to do it but must've forgotten. So the ground was intermittent and causing my guage problems I assume. I haven't tightened them yet as the car is hot and I'm about to go on vacation for the weekend, but I'll do it first thing when I get back and see if it fixes my problems. Thanks for the help so far.
