12 replies to this topic

[brivinci]

Hey all. My tuned 94 SPi has had a strange flat spot in its rev range for some time now. It's not always present but seems to be more lately. The problem is really prevalent in 3rd and 4th...the gears that use it the most and especially uphill. All that indicated it's when the more is under its most load? Weird thing is, when you break past 4k, the motor revs cleanly to red line.

Lately, I have felt this feel a lot like a misfire, where you can feel/hear the sputtering. Even without, it's a very noticeable flat spot that the motor struggles to overcome. I was wondering if capturing data would be useful here and which would work best and if one type of data is better than another? Sadly for me, I am a Mac user and it seems most MEMs apps only run on PC. I have one for my Mac but I am not sure if would capture what would be most helpful. I have build the proper cable to connect and have been able to get it to view live data. Tried with a PC but man am I rubbish with PC. I had no clue how to work/find anything. 

My car has had a fair amount of the usual work done, but running the standard Rover injection/ECU. Motor is a 1310 with a Calver ST ported head and custom cam to match, 1.5 roller tip rockers, Maniflow LCB and twin box system with CAT delete, K&N drop in filter. The vac lines are all proper thick-walled silicone, I just replaced a leaking fuel trap and replaced the crank sensor as the tip of mine looked worn, oddly enough. Running a MED lightened flywheel with integrated timing marks (no slipped ring like stock could have). Recently replaced the coil with a standard one from spares. Cap and rotor are newer with high quality wires from Swiftune. Car has 69k on the clock and I am the second owner. Was bone stock when I got it. All wiring is original and in great shape. Motor has been in and out a handful of times over the 20+ years of ownership. Anything I find an issue I try and sort with only genuine replacement parts (outside of performance items). Fuel pump is original and the evaporator system is still present. I run 92 octane or higher here in the US. Timing was set off the cam to Calvers recommendation for cam profile using a dial gauge and wheel on an adjustable timing set.

Wondering what you all think could be causing this issue as such a specific point in the rev range, and the fact that it most noticeable in 3rd and 4th. Appreciate any help. 

[genpop]

Hi Brian,

memsfcr is for mac too.

https://memsfcr.co.uk/download/

 

if you have somebody who can compile code for the mac, i give you the complete code for mems-rosco.

[Steam]

You have not said what distributor and ignition system you have, points, module or electronic dissy.
It could be mixture issues or equally ignition problems, it will be trial and error to find it.

[FlyingScot]

Steam it’s an SPi. The dizzy is just a shell and the MEMS ECU controls the spark all be it using a coil on this model.

 

I would start with the basics - mechanical checks first, tappets and valve lift/sealing. Then fuel filter. 
 

Is the coil change you mentioned recent to try and clear the fault ? As I have had on an SPi a coil which broke down under load and when it got warm.

 

FS

[brivinci]

Yes, the distributor is the stock, gutted Rover one with just a rotor inside. ECU controls start. 

I replaced the original coil years ago just to be safe...which never works out for me. The new one eventually failed, and pretty suddenly. I was driving home and suddenly the car was cutting in and out and then nothing. Oddly enough, I either ordered 2 or Spares sent me an extra by mistake so I had another to swap over. Fired right up after. I bet my original is still perfectly fine still. ha.

 

As I had the motor out to sort a leaking half moon and main seal, I went through and adjusted all the rockers. These are MED 1.5 roller tips. Lovely bit of kit but I should have ordered 1.3s I feel. This isn't a race car and the cam is already pretty hot. 

 

I was meant to replace the fuel filter 5 months ago BUT I I'm 7k miles under the 12,000mi change rate. Going by the 16 months I guess. I have one standing by, just have to get under it. Will do that asap. 

I wrote about a possible fuel pump replacement. Again, just something I figure would be good to replace (maybe not) due to age. Car is 30 years old this year and just turned 69k on the clock. Due to the fact that this happens at that specific RPM range, and very noticeable in 3rd, and 4th, I doubt that is it though.

 

 

Oh, I could run a compression and leak down test rule anything there out as well. I'll add that to my list.

Edited by brivinci, 29 April 2024 - 09:23 PM.

[brivinci]

Hi Brian,

memsfcr is for mac too.

https://memsfcr.co.uk/download/

 

if you have somebody who can compile code for the mac, i give you the complete code for mems-rosco.

 

genpop, I do actually have this downloaded on a MAC and have connected it successfully. Due to it being web based, I'll have to try and hotspot off phone so I can have it run while driving. Does this record data and save that somewhere? Would like to do a few pulls in 3rd and 4th and see if I can replicate it. I was thinking, if nothing else, I could do a screen recording of it while driving and share that? For yourself, what is the most important screen to be viewing while on the road and what do you think will tell the potential story here? 

[genpop]

Hi Brian,

1. there is another good software for the android here: https://rovermems.com/diagnostics/

2.I#m not used to the mac software, so I do not know where it stores its logs.Best you ask Andrew direct or here on the forum.

3. In my opinion, a single picture of readings says nothing.Yo can only diagnose a run if you have the log and compare two or more curves to each other.Therefore you must see them one over the other.If you have an abnormality in one curve  you check the other curves at that point too.If you can`diagnose on Andrews webside there are some logreaders on the web.

On a pc you would find the log at c:/users/your name/AppData/Local/Memsfcr/logs

So best you start a search for memsfcr!

4.You have too much money, you change parts which are good and working.Never touch a running system

[Midas Mk1]

Have you continuity checked and visually inspected the engine bay harness? I’ve been chasing issues with my 7yr old sc setup, found plenty of high resistance, corrosion in the loom at the crank sensor, tps and coil pack connector. All of which contributed to a fluffiness at 3k and a rough drive, just a thought, as the loom is touching 30 years old now on a SPi.

[brivinci]

Sadly, I feel like I am at that point of checking the harness. I have not had to touch it at all all these years, sort of replacing a few in-line fuse holders and spade ends. I have always loved that this car has had so little done, outside what I have done and I know was done right. Getting cars with previous "fixes" made to the wiring has never worked out. The nightmares always seem to show up.
It's funny but one of plans would be to swap over to a SC setup. I have always felt like cars current setup has more to give, if it was given the chance. BUT it still requires the original wires to be in tip top shape. Can I ask what was causing the high resistance? Just corrosion or were wires beginning to crack? 

I agree completely with you Genpop! I am not one to just throw money at a problem. The items I replaced were never to cure an issue but to hope for it to never fail. The goal for this car is has always been that it could go anywhere, anytime. 1000 miles in a weekend, no problem. Drive across the US to California (that is still a plan), why not! I also keep all the original parts/sensors as backups. 

 

Sorry, what I meant by a screen recording was that I could video record my screen with the data running live, not a still. Even so, probably not that helpful. Might need to talk to someone with more PC knowledge and see if they can help me out on this. I feel like that is the best place to start. just to get a better idea what exactly is going on...and if this system has the ability to see anything.

[genpop]

Hi Brian.

do you have an Android, so take one of the android programs on google store or the one of James portman.Have you already visited the sides of James or  Andrew, both have good explanations on their software. Additionally I remember you had a laptop with mems-rosco on it.mems-rosco is very good for examining the logs.Of course you can take excel for this too.

rovermems.com or memsfcr.uk

On screen records you can not compare the readings of sensors or you write them all down in an excel sheet,............. nice work.

[Midas Mk1]

My high resistance was down to corrosion, it's a daily all year round car, to be honest my first step would be checking resistance of each terminal on the relevant connector to the pinout on the ecu connector, quick and easy way to check. 

[Midas Mk1]

Alsoooooo, as i’ve found at work, repeat pinout to each terminal test, whilst moving the wiring, remember 0.3ohms is ideal.

Edited by Midas Mk1, 01 May 2024 - 07:05 PM.

[brivinci]

As it turns out....I now have my very first short!! I just noticed that my fog lights are shorting and blowing the inline fuse. I have had the grill on and off a handful of times lately and I bet I just pinched a wire but it's just funny it should happen while we are talking about wiring. 

I am about to go in for shoulder surgery tomorrow so will be laid up for some time. Wish I had the loom on a desk as it would make for a nice, easy project while Im in a sling. I understand the ol adage, "if it aint broke, don't fix it" but love the idea of extending things. Would love to pull the entire loom, uncover, test/inspect, and rewrap it all. Sounds like a nightmare to most but it would give me great satisfaction to know its been done. Maybe a goo winter project one of these years:-)